Process for the preparation of substituted prolyl peptides and similar peptidomimetics

ABSTRACT

The present invention relates to a process for the stereoselective preparation of a compound having the general formula (I) or its respective diastereomers: comprising reacting a compound having the general formula (II) or its diastereomers: with a compound of the general formula III: R 3 —COOH and a compound of the general formula IV: R 4 —NC wherein R 1  represents each independently, or jointly a substituted or unsubstituted alkyl, alkenyl, alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic, or heterocyclic structure, and R 2  represents a hydrogen atom, a substituted or unsubstituted alkyl, alkenyl, alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic, or heterocyclic structure, and R 3  represents a substituted or unsubstituted alkyl, alkenyl, or alkynyl, or an aromatic or non-aromatic aromatic or non-aromatic, mono-, di- or tricyclic, or heterocyclic structure. 
                         R 3 —COOH  (III)
 
       R 4 —NC  (IV)

FIELD OF THE INVENTION

The present invention relates to substituted prolyl peptides and similarpeptidomimetics, methods for their preparation, and a variety of usesincluding as inhibitors of disease-associated targets as well as anorganocatalyst component.

BACKGROUND TO THE INVENTION

Optically pure 3,4-substituted prolyl peptides and relatedpeptidomimetic compounds are of considerable interest in organocatalysisand medicinal chemistry, specifically since they form key structuralelements of the hepatitis C virus NS3 protease inhibitors telaprevir andboceprevir as disclosed in for instance WO2003/062265.

Multicomponent reactions (MCRs) offer the ability to rapidly andefficiently generate collections of structurally and functionallydiverse organic compounds. Although MCRs are very efficient by theirnature, the stereocontrol in these reactions is mostly not trivial.

The Ugi reaction is undoubtedly one of the most widely applied MCRs. Itis of considerable interest owing to its exceptional syntheticefficiency and is widely used in the field of modern combinatorial andmedicinal chemistry. The Ugi reaction involves a one-pot condensation ofan aldehyde, an amine, a carboxylic acid and an isocyanide to producechiral α-acylaminoamides. In 1982, Nutt and Joullie reported a variationon the Ugi reaction (further referred to herein as Joullie-Ugi reaction,or JU-3CR), which employed substituted 1-pyrrolines to producesubstituted prolyl peptides. However, as in most MCRs, controlling thenewly formed stereocenter proves highly complex, and therefore thereaction suffers from poor and/or unpredictable (dia)stereoselectivity,as illustrated for instance by WO2006/061585. This document discloses aJU-3CR employing dihydroxypyrolline compounds to form peptidomimeticcompounds comprising dihydroxyproline structures. The reported productsare formed in only limited yields and mostly unpredictablediastereoselectivity, while requiring the use of protecting groups thatare often difficult to remove, such as benzyl groups.

Accordingly, the known multicomponent reactions for the preparation ofproline derivative comprising peptides and peptidomimetics suffer frompoor and/or unpredictable (dia)stereoselectivity. Alternative processschemes are tedious, require numerous steps and hence suffer from lowyields.

Notwithstanding the state of the art it would be desirable to provide anenantioselective Joullie-Ugi reaction, or JU-3CR for preparingsubstituted prolyl peptide structures.

SUMMARY OF THE INVENTION

The present invention relates to a stereoselective process for thepreparation of a compound having the general formula Ia or Ib:

comprising reacting a compound having the general formula II or itsdiastereomers:

with a compound of the general formula III:

R³—COOH  (III)

and a compound of the general formula IV:

R⁴⁻—NC  (IV)

wherein R¹ represents each independently, or jointly a substituted orunsubstituted lower alkyl, alkenyl, alkynyl, aromatic or non-aromatic,or heterocyclic structure, and

wherein R² represents each independently a hydrogen, or eachindependently or jointly a substituted or unsubstituted alkyl, alkenyl,alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic, orheterocyclic structure, and

R³ represents a substituted or unsubstituted alkyl, alkenyl, alkynyl,aromatic or non-aromatic, mono-, di- or tricyclic, heterocyclic,alkyloxy, alkanoyl, amino, ureido or a peptide structure, and

R⁴ represents a substituted or unsubstituted alkyl, alkenyl, or alkynyl,or an aromatic or non-aromatic aromatic or non-aromatic, mono-, di- ortricyclic, or heterocyclic alkyl, alkenyl, alkynyl, aromatic ornon-aromatic, mono-, di- or tricyclic, heterocyclic, alkyloxy, alkanoyl,amino, ureido or a peptide structure.

In the subject process, stereoselectivity refers to enantioselectivityor diastereoselectivity, depending on the substrates.

As used herein, the term “alkyl” denotes a saturated straight orbranched hydrocarbon chain comprising carbon and hydrogen atoms, forexample, methyl, ethyl, propyl, isopropyl, n-butyl, i-butyl, 2-butyl,t-butyl and the like. Preferred alkyl groups are groups with 1-10 carbonatoms.

The term “alkyloxy” denotes an alkyl group as defined above, which isattached via an oxygen atom.

The term “alkyl substituted by halogen” denotes an alkyl group asdefined above, wherein at least one hydrogen atom is replaced byhalogen, for example CF₃, CHF₂, CH₂F, CH₂CF₃, CH₂CH₂CF₃, CH₂CF₂CF₃ andthe like. The term “halogen” denotes chlorine, iodine, fluorine andbromine.

The term “cycloalkyl” denotes a saturated carbocyclic ring, preferablycontaining from 3 to 10 carbon atoms, more preferably 3 to 8 carbonatoms, yet more preferably from 3 to 6 carbon atoms, for example,cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

The term “cycloalkenyl” denotes a saturated carbocyclic ring, preferablycontaining from 3 to 10 carbon atoms, more preferably 3 to 8 carbonatoms, yet more preferably from 3 to 6 carbon atoms, for example,cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

The term cyclocalkyl preferably comprises (C₁-C₁₀) alkyl. The term“(C₁-C₁₀) alkyl” means a straight chain or branched non cyclichydrocarbon having from 1 to 10 carbon atoms. Representative straightchain —(C₁-C₁₀) alkyls include (C₁, C₂, C₃, C₄, C₅, C₆, C₇, C₈, C₉ andC₁₀ alyls, such as -methyl, -ethyl, -n propyl, -n-butyl, -n-pentyl,-n-hexyl, -n-heptyl, -n-octyl, -n-nonyl, and -n-decyl.

A branched alkyl means that one or more straight chain —(C₁-C₈) alkylgroups, such as -methyl, -ethyl or -propyl, replace one or bothhydrogens in a —CH₂— group of a straight chain alkyl. A branched noncyclic hydrocarbon means that one or more straight chain (C₁-C₁₀) alkylgroups, such as -methyl, -ethyl or -propyl, replace one or bothhydrogens in a —CH₂— group of a straight chain non cyclic hydrocarbon.

The term “—(C₁-C₂)alkyl” means a straight chain non cyclic hydrocarbonhaving 1 or 2 carbon atoms. Representative straight chain “—(C₁-C₂)alkylgroups include -methyl and -ethyl.

The term “(C₁-C₃)alkyl” means a straight chain or branched non cyclichydrocarbon having from 1 to 3 carbon atoms. Representative straightchain (C₁-C₃)alkyl groups include -methyl, -ethyl, and -n-propyl.Representative branched —(C₁-C₃)alkyl groups include -iso-propyl.

The term “(C₁-C₄)alkyl” means a straight chain or branched non cyclichydrocarbon having from 1 to 4 carbon atoms. Representative straightchain —(C₁-C₄)alkyl groups include -methyl, -ethyl, -n-propyl, and-n-butyl. Representative branched —(C₁-C₄)alkyls include -iso-propyl,-sec-butyl, -iso-butyl, and -tert-butyl. The term “(C₁-C₆)alkyl” means astraight chain or branched non cyclic hydrocarbon having from 1 to 6carbon atoms. Representative straight chain —(C₁-C₆)alkyls include-methyl, -ethyl, -n-propyl, -n-butyl, -n-pentyl, and -n-hexyl.Representative branched (C₁-C₆)alkyls include iso-propyl, -sec-butyl,-iso-butyl, -tert-butyl, -iso-pentyl, -neopentyl, 1-methylbutyl,2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl,1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl,1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, 1,1-dimethylbutyl,1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl,2,3-dimethylbutyl, and 3,3-dimethylbutyl.

Representative branched —(C₁-C₁₀) alkyl groups include iso-propyl,sec-butyl, iso-butyl, tert-butyl, iso-pentyl, neopentyl, 1-methylbutyl,2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl,1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl,1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, 1,1-dimethylbutyl,1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl,2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-methylhexyl, 2-methylhexyl,3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1,2-dimethylpentyl,1,3-dimethylpentyl, 1,2-dimethylhexyl, 1,3-dimethylhexyl,3,3-dimethylhexyl, 1,2-dimethylheptyl, 1,3-dimethylheptyl, and3,3-dimethylheptyl.

The term “(C₂-C₁₀)alkenyl” means a straight chain or branched non cyclichydrocarbon having from 2 to 10 carbon atoms and including at least onecarbon-carbon double bond. A branched alkenyl means that one or morestraight chain —(C₁-C₈)alkyl groups, such as -methyl, -ethyl or -propyl,replace one or both hydrogens in a —CH₂— or —CH═ group of a straightchain alkenyl. Representative straight chain and branched(C₂-C₁₀)alkenyl groups include -vinyl, -allyl, 1-butenyl, -2-butenyl,-iso-butylenyl, -1-pentenyl, -2-pentenyl, -3-methyl-1-butenyl,2-methyl-2-butenyl, -2,3-dimethyl-2-butenyl, -1-hexenyl, -2-hexenyl,-3-hexenyl, -1-heptenyl, -2-heptenyl, -3-heptenyl, -1-octenyl,-2-octenyl, -3-octenyl, -1-nonenyl, -2-nonenyl, -3-nonenyl, -1-decenyl,-2-decenyl, -3-decenyl, and the like.

The term “C₁-C₆)alkoxy” represents a straight chain or branched noncyclic hydrocarbon having one or more ether groups and from 1 to 6carbon atoms. Representative straight chain and branched C₁-C₆)alkoxygroups include -methoxy, -ethoxy, -methoxymethyl, -2-methoxyethyl,-5-methoxypentyl, -3-ethoxybutyl and the like.

The term “C₃-C₁₂ cycloalkyl” groups refers to a saturated monocyclichydrocarbon having from 3 to 12 carbon atoms. Representative C₃-C₁₂cycloalkyl groups are -cyclopropyl, -cyclobutyl, -cyclopentyl,-cyclohexyl, -cycloheptyl, -cyclooctyl, -cyclononyl, -cyclodecyl, and-cyclododecyl.

“C₄-C₈ cycloalkyl” groups refers to “4- to 8-member cycloalkyl rings”,meaning a saturated monocyclic hydrocarbon having from 4 to 8 carbonatoms. Representative —C₄-C₈ cycloalkyl groups are -cyclobutyl,-cyclopentyl, -cyclohexyl, -cycloheptyl, and -cyclooctyl.

C₃-C₈ cycloalkyl groups mean a saturated monocyclic hydrocarbon havingfrom 3 to 8 carbon atoms. Representative C₃-C₈ cycloalkyl groups include-cyclopropyl, -cyclobutyl, -cyclopentyl, -cyclohexyl, -cycloheptyl, and-cyclooctyl.

C₃-C₇ cycloalkyl groups means a saturated monocyclic hydrocarbon havingfrom 3 to 7 carbon atoms. Representative C₃-C₇ cycloalkyl groups include-cyclopropyl, -cyclobutyl, -cyclopentyl, -cyclohexyl, and -cycloheptyl.

“-(6- to 10-membered) heterobicyclic” or “-(6- to 10-membered)bicycloheterocyclo” group refers to a 6 to 10 membered bicyclic,heterocyclic ring which is either saturated, unsaturated non-aromatic,or aromatic. A -(6- to 10-membered)heterobicyclic group contains from 1to 4 heteroatoms independently selected from nitrogen, which can bequaternized; oxygen; and sulfur, including sulfoxide and sulfone. The-(6- to 10-membered)heterobicyclic group can be attached via a nitrogenor carbon atom. Representative -(6- to 10-membered)heterobicyclic groupsinclude-3-azabicyclo[3.1.0]hexane, -quinolinyl, -isoquinolinyl,-chromonyl, -coumarinyl, -indolyl, -indolizinyl, benzo[b]furanyl,benzo[b]thiophenyl, -indazolyl, -purinyl, -4H-quinolizinyl, isoquinolyl,-quinolyl, -phthalazinyl, -naphthyridinyl, -carbazolyl,-[beta]-carbolinyl, -indolinyl, -isoindolinyl,-1,2,3,4-tetrahydroquinolinyl, -1,2,3,4-tetrahydroisoquinolinyl,pyrrolopyrrolyl and the like.

The term “CH₂(halo)” group means a methyl group where one of thehydrogens of the methyl group has been replaced with a halogen.Representative —CH₂(halo) groups include —CH₂F, —CH₂Cl, —CH₂Br, and—CH₂I.

The term “—CH(halo)₂” means a methyl group where two of the hydrogens ofthe methyl group have been replaced with a halogen. Representative—CH(halo)₂ groups include —CHF₂, —CHCl₂, —CHBr₂, —CHBrCl, —CHClI, and—CHI₂.

The term “—C(halo)₃” means a methyl group where each of the hydrogens ofthe methyl group has been replaced with a halogen. Representative—C(halo)₃ groups include —CF₃, —CCl₃, —CBr₃, and —Cl₃.

“-Halogen” or “-halo” means —F, —Cl, —Br, or —I.

“Oxo”, “═O”, and the like as used herein mean an oxygen atom doublybonded to carbon or another element.

When a first group is “substituted with one or more” second groups, oneor more hydrogen atoms of the first group are replaced with acorresponding number of second groups. When the number of second groupsis two or greater, each second group can be the same or different.

The term “aryl” as used herein is a carbocyclic ring system, containingfrom 6 to 10 carbon atoms forming one or more rings, and wherein atleast one ring is aromatic in nature, for example phenyl, naphthyl or5,6,7,8-tetrahydronaphthalen-1-yl. The most preferred aryl group isphenyl.

The term “enantiomeric excess” refers to a difference between the amountof one enantiomer and the amount of the other enantiomer that is presentin the product mixture. Thus for example, enantiomeric excess of 96%refers to a product mixture having 98% of one enantiomer and 2% of theother enantiomer.

The terms “enantiomeric excess” and “diastereomeric excess” are usedinterchangeably herein. Compounds with a single stereocenter arereferred to as being present in “enantiomeric excess,” those with atleast two stereocenters are referred to as being present in“diastereomeric excess.” In the graphic representations of racemic orenantiomerically pure compounds used herein, solid and broken wedges areused to denote the absolute configuration of a chiral element; wavylines indicate disavowal of any stereochemical implication which thebond it represents could generate; solid and broken bold lines aregeometric descriptors indicating the relative configuration shown butnot implying any absolute stereochemistry; and wedge outlines and dottedor broken lines denote enantiomerically pure compounds of indeterminateabsolute configuration.

The term “heterocyclic” embraces both “heteroaryl” and“heterocycloalkyl” groups. The term “heteroaryl” as used herein is anaromatic ring system, containing from 5 to 10 ring atoms forming one ormore rings, wherein at least one ring atom is a heteroatom selected fromthe group consisting of O, N and S, and wherein at least one ring isaromatic in nature, for example oxazolyl, pyridyl, thiophenyl,quinolinyl, pyrrolyl, furyl, benzoimidazolyl, imidazolyl and the like.The most preferred group is pyridyl.

The term “heterocycloalkyl” denotes a fully saturated ring system,wherein one or two ring atoms are N, O or S, for example piperazinyl,pyrrolidinyl, morpholinyl or piperidinyl.

The term “monoamine oxidase” refers to a polypeptide having an enzymaticcapability of oxidizing a compound of structural Formula I, supra to thecorresponding product of structural Formula II, supra. The polypeptidetypically utilizes an oxidized cofactor, such as but not limited toflavin adenine dinucleotide (FAD), flavin adenine mononucleotide (FMN),nicotinamide adenine dinucleotide (NAD), or nicotinamide adeninedinucleotide phosphate (NADP). In a particular embodiment, the oxidizedcofactor is FAD. Monoamine oxidases as preferably used herein includenaturally occurring (wild type) monoamine oxidases as well asnon-naturally occurring engineered polypeptides generated by humanmanipulation.

The term “naturally occurring” or “wild type” refers to a polypeptideoccurring in nature. For example, a naturally occurring or wild typepolypeptide or polynucleotide sequence is a sequence present in anorganism that can be isolated from a source in nature and which has notbeen intentionally modified by human manipulation.

The term “peptide” denotes polymers of amino acids linked by peptidebonds.

The term “peptidomimetics” denotes structures that resemble polymers ofamino acids linked by peptide bonds, either comprising non-naturallyoccurring α-, β- or similar amino acids, or using structurally differentbuilding blocks.

“Pharmaceutically acceptable” such as pharmaceutically acceptable salt,carrier, excipient, etc., means pharmacologically acceptable andsubstantially non-toxic to the subject to which the particular compoundis administered.

The term “pharmaceutically acceptable salt” embraces salts withinorganic and organic acids, such as hydrochloric acid, nitric acid,sulfuric acid, phosphoric acid, citric acid, formic acid, fumaric acid,maleic acid, acetic acid, succinic acid, tartaric acid, methane-sulfonicacid, p-toluenesulfonic acid and the like.

The term “Pharmaceutically acceptable N-oxide” refers to N-oxides oftertiary nitrogen atoms in a molecule, which may be more potent thantheir corresponding tertiary amine, or less. N-oxides may or may not bereduced to their corresponding tertiary amines after indigestion. WhenN-oxides are converted to their corresponding tertiary amines, theconversion may be in mere trace amounts or nearly quantitative. Further,once formed, N-oxides may be more active than their correspondingtertiary amines, less active or even completely inactive.

The term “prodrug” refers to a precursor form of the compound that ismetabolized to form the active ingredient.

The term “stereoselective” refers to the preferential formation in achemical or enzymatic reaction of one stereoisomer over another.Stereoselectivity can be partial, where the formation of onestereoisomer is favoured over the other, or it may be complete whereonly one stereoisomer is formed. When the stereoisomers are enantiomers,the stereoselectivity is referred to as enantioselectivity, the fractionreported as a percentage of one enantiomer in the sum of both. It iscommonly alternatively reported in the art (typically as a percentage)as the enantiomeric excess (e.e.) calculated therefrom according to theformula [major enantiomer−minor enantiomer]/[major enantiomer+minorenantiomer]. Where the stereoisomers are diastereoisomers, thestereoselectivity is referred to as diastereoselectivity, the fraction(typically reported as a percentage) of one diastereomer in a mixture oftwo diasteromers, commonly alternatively reported as the diastereomericexcess (d.e.). Enantiomeric excess and diastereomeric excess are typesof stereomeric excess. The present process allows a stereoselectivepreparation of the desired compounds in a simple an convergent manner,yielding the desired enantiomers—or diastereomers based on easilyavailable chiral information preferably derived from 3R,4S- or3S,4R-configured pyrrolidine compounds.

The term “stereospecificity” refers to the preferential conversion in achemical or enzymatic reaction of one stereoisomer over another.Stereospecificity can be partial, where the conversion of onestereoisomer is favored over the other, or it may be complete where onlyone stereoisomer is converted.

The term “chemoselectivity” refers to the preferential formation in achemical or enzymatic reaction of one product over another.

“Therapeutically effective amount” means an amount that is effective toprevent, alleviate or ameliorate symptoms of disease or prolong thesurvival of the subject being treated.

As used herein, the terms “stereoisomer”, “stereoisomeric form” and thelike are general terms for all isomers of individual molecules thatdiffer only in the orientation of their atoms in space. It includesenantiomers and isomers of compounds with more than one chiral centerthat are not mirror images of one another (“diastereomers”).

The term “chiral centre” refers to a carbon atom to which four differentgroups are attached.

The term “enantiomer” or “enantiomeric” refers to a molecule that isnon-superimposeable on its mirror image and hence optically active wherethe enantiomer rotates the plane of polarized light in one direction andits mirror image rotates the plane of polarized light in the oppositedirection.

The term “racemic” refers to a mixture of equal parts of enantiomerswhich is optically inactive.

The term “resolution” refers to the separation or concentration ordepletion of one of the two enantiomeric forms of a molecule.

“Substantially enantiomerically pure” as used herein means that theindicated enantiomer of a compound is present to a greater extent ordegree than another enantiomer of the same compound. Accordingly, inparticular embodiments, a substantially enantiomerically pure compoundis present in 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or99% enantiomeric excess over another enantiomer of the same compound.

“Substantially stereomerically pure” as used herein means that theindicated enantiomer or diastereomer of a compound is present to agreater extent or degree than another enantiomer or diastereomer of thesame compound. As noted above with respect to “stereoselectivity”,enantiomeric excess and diastereomeric excess are types of stereomericexcess. Accordingly, in particular embodiments, a substantiallystereomerically pure compound is present in 80%, 85%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, or 99% stereomeric excess over anotherenantiomer or diastereomer of the same compound.

Unlike prior art processes for the enantioselective preparation ofcompounds according to formula (I), the process of the present inventionallows for the synthesis of either enantiomer of according to formula(I) in excellent yield and enantiomeric excess at mild conditions, andin a very small number of steps. In addition, the inventive process ofthe present invention allows for very effective use of readily availablechiral starting information. Insofar, the process of the presentinvention is highly efficient as it does not produce 50% of the unwantedenantiomer. These advantages combine to make the process of the presentinvention very economic and amenable to industrial scale up.

The process according to the invention advantageously allows for theenantioselective formation of products, i.e., may produce productshaving a high enantiomeric excess. An “enantioselective” processaccording to the invention hence results in the formation of a productwith an enantiomeric excess and/or diastereomeric excess of the desiredrespective enantiomer or diastereomers.

In an exemplary embodiment, the method produces the product with anenantiomeric excess of a product from 80% ee (de) to >99.9% ee (de),more preferably from 90% ee (de) to 99.9% ee (de), yet more preferablyfrom 95% ee (de) to >99.7% ee (de), still more preferably from 98% ee(de) to >99.5% ee (de), still more preferably from 99.0% ee (de) to morethan 99.3% ee(de).

For analysis of yield, diastereomeric and/or enantiomeric excess, theproduct may be analyzed by NMR (e.g., ¹H NMR, ¹³C NMR, etc.), HPLC, GLC,or the like. In some cases, more than one analysis may be performed. Forexample, a product may be analyzed by NMR, wherein the presence ofdifferent enantiomers may be indicated by NMR peaks characteristic of aparticular enantiomer upon addition of a chiral shift reagent. In someembodiments, the product may be analyzed using chromatography (e.g.,HPLC or GLC), where different enantiomers or diastereomers may exhibitdistinct retention times. Yet further, crystallographic evidence may beemployed where a product of intermediate can be crystallized to suchform that supports a sutibale analysis. A person skilled in the art willbe able to determine the appropriate method, or combination of methods,to utilize based upon the product to be analyzed.

DETAILED DESCRIPTION OF THE INVENTION

In the process according to the invention, the use of the opticallyactive 1-pyrroline compounds of formula II and the diastereomers in areaction with compounds of general formula (III) and (IV) resulted inthe formation of compounds (I) with an unprecedentedly high(dia)stereoselectivity and yield. Without wishing the bound to anyparticular theory, it is believed that the steric bulk of thesubstituents at the 3 and 4 position of the pyrroline compoundsaccording to formula IIa or b directs the addition of nucleophiles tothe imine with high diastereoselectivity.

The 1-pyrroline compound according to formula II may be convenientlyprepared by the desymmetrization of 3,4-substituted meso-pyrrolidines.This may advantageously be performed in a biocatalytic process, such asa process comprising treating the meso-pyrrolidines with an enzymecapable of catalysing oxidation of the amine in an enantioselectivemanner to form compound II.

In the case of R² being different from hydrogen, the diastereomers ofcompound II referred to above include the following compounds of generalformula IIa and IIb:

which will result predominantly in the formation of the respectivestereoisomers of compound I according to general formula Ia and Ib:

The (3R,7S)-diastereomers IIc and IId, i.e. the diastereomers having theopposite configuration of the substituents R² can also be employed,yielding the equivalent (3R,7S)-configured proline derivatives Ic andId.

Monoamine oxidase enzymes suitable for use in biocatalytic process havebeen used to resolve and deracemize racemic chiral amines via thestereospecific oxidation of one enantiomer to the corresponding imineusing oxygen. Derivatives of the flavin dependent monoamine oxidase ofAspergillus niger (MAO N) (Shilling et al. et al. (1995) Biochim.Biophys. Acta. 1243: 529 37) have been reported as useful, incombination with non specific chemical reducing agents, for thederacemization of (d/1) α-methylbenzylamine to provide enantiomericallypure (93% ee) (d/l) α-methylbenzylamine (Alexeeva et al. (2002), Angew.Chem. Int. Ed. 41: 3177-3180). Derivatives of the flavin dependentmonoamine oxidase of Aspergillus niger were also used for deracemizationof (R/S)-2-phenypyrrolidine to provide enantiomerically pure (98% ee)(R)-2-phenypyrrolidine (Carr et al. (2005), ChemBioChem 6: 637 39; Gotoret al. “Enantioselective Enzymatic Desymmetrization in OrganicSynthesis,” Chem. Rev. (2005) 105: 313.

Preferably the biocatalytic desymmetrization comprises treatingsubsequently or simultaneously in situ the obtained oxidised amine witha chemical reducing agent, more preferably a non-enantioselectivereducing agent, yet more preferably a reducing agent selected fromsodium borohydride, sodium cyanoborohydride, an amine-borane complex ora transfer hydrogenation agent.

More preferably, the enzyme is a microbial monoamine oxidase, preferablya monoamine oxidase N derived from naturally occurring, selectively bredor genetically modified Aspergillus species, preferably A. niger.

Most preferably, the biocatalytic desymmetrization is performed usingthe monoamine oxidase N (MAO-N) from Aspergillus niger according to themethod disclosed in WO03080855, and in J. Turner et al., Angew. Chem.Int. Ed. 2002, 41, 3177-3180; and Turner et al., Angew. Chem. Int. Ed.2003, 42, 4807-4810.

R¹ according to the invention may each independently or jointly be thesame group, and preferably represents a hydrogen atom, a halogen atom, ahydroxyl group, a nitro group, a formyl group, an amino group which maybe protected or substituted, a lower alkyl, cycloalkyl, aryl, loweralkoxy, cycloalkyloxy, aralkyloxy, alkanoyl, ureido or monocyclicheterocyclic group. Suitable imino compounds according to formula II arethose disclosed in WO-A-2010/008828, more advantageously n paragraph[27] and [29] of this publication.

More preferably, both substituents R¹ jointly form an optionallysubstituted 3-, 4-, 5-, 6-, 7- or 8 membered ring structure. This ringstructure jointly formed by the substituents R¹ may preferably be asaturated or unsaturated, mono-, bi- or tricyclic, (C₁-C₁₀) alkyl,(C₂-C₁₀)alkenyl, C₁-C₆)alkoxy C₃-C₁₂ cycloalkyl CH₂(halo), —CH(halo)₂ or—C(halo)₃, heterocyclic such as heterocycloalkyl structure. The prolinering together with the ring structure formed by the substituents R¹ mayadvantageously be bi- or tri-cyclic or of a higher annealed order.

Preferred embodiments of the process according to the invention employcompounds according to formula II with the structure according togeneral formula V, or the opposite enantiomer:

according to formula VI, or the opposite enantiomer:

according to formula VII, or the opposite enantiomer:

R² preferably represents a hydrogen atom, a (lower) alkyl group,preferably comprising from 1 to 4 carbon atoms, a lower alkyl groupsubstituted by halogen, a cycloalkyl group, a (lower) alkoxy group, a(lower) thioalkyl group, a cycloalkyloxy group, an aralkyloxy group oran alkanoyl group; a hydroxyl group which may be protected orsubstituted, a nitro group, a formyl group, an amino group which may beprotected or substituted, a cycloalkyloxy, aralkyloxy, alkanoyl, ureidoor mono-, di- or tricyclic heterocyclic group, all of which groups mayoptionally be substituted.

R³ preferably represents a hydrogen atom, a lower alkyl group comprisingfrom 1 to 4 carbon atoms, a lower alkyl group substituted by halogen, acycloalkyl group, an aryl group, a lower alkoxy group, a lower thioalkylgroup, a cycloalkyloxy group, an aralkyloxy group or an alkanoyl group;a hydroxyl group, a nitro group, a formyl group, an amino group whichmay be protected or substituted, a cycloalkyloxy, aralkyloxy, alkanoyl,ureido or mono-, di- or tricyclic heterocyclic group, all of whichgroups may optionally be substituted.

More preferably, R³ represents a compound according to general formulaVIII:

wherein R^(a) and R^(b) each independently represents a hydrogen atom, a(lower) alkyl group preferably comprising from 1 to 4 carbon atoms, a(lower) alkyl group substituted by halogen such as a —CH₂(halo), a—CH(halo)₂ or a —C(halo)₃ group, a cycloalkyl group, an aryl group, alower alkoxy group, a lower thioalkyl group, a cycloalkyloxy group, anaralkyloxy group or an alkanoyl group; a hydroxyl group, a nitro group,a formyl group, an amino group which may be protected or substituted, acycloalkyloxy, aralkyloxy, alkanoyl, ureido or mono-, di- or tricyclicheterocyclic group, all of which groups may optionally be substituted.

R^(a) preferably represents a branched alkyl group, more preferably a C₃or C₄ alkyl group, and most preferably a tertiary butyl group.

R^(b) preferably represents a (C₁-C₁₀) alkyl, (C₂-C₁₀)alkenyl,—(C₁-C₆)alkoxy, —(C₃-C₁₂)cycloalkyl, —CH₂(halo), —CH(halo)₂ or—C(halo)₃, heterocyclic such as heterocycloalkyl group, or morepreferably a N-tert-butyl amino group or acyclohexyl-2-(pyrazine-2-carboxamido)acetamido) group, in particular forthe synthesis of(S)-2-((S)-2-cyclohexyl-2-(pyrazine-2-carboxamido)acetamido)-3,3-dimethylbutanoicacid.

R⁴ preferably represents a lower alkyl group comprising from 1 to 4carbon atoms, a lower alkyl group substituted by halogen, a cycloalkylgroup, an aryl group, a lower alkoxy group, a lower thioalkyl group, acycloalkyloxy group, an aralkyloxy group or an alkanoyl group; ahydroxyl group, a nitro group, a formyl group, an amino group which maybe protected or substituted, a cycloalkyloxy, aralkyloxy, alkanoyl,ureido or mono-, di- or tricyclic heterocyclic group, all of whichgroups may optionally be substituted.

In a preferred embodiment of the subject process, the compound accordingto general formula IV preferably has a structure according to generalformula IX

wherein R^(d), R^(e) and R^(f) each independently represents a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl, alkenyl,alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic and/or aheterocyclic group.

Such compounds may advantageously be prepared from precursor compoundsof the general formula X by dehydration under suitable conditions.

Accordingly the present process further comprises:

A1) reacting a compound of the general formula XI:

with a compound of the formula XII:

R^(e)—COOH  (XII),

and a compound of the general formula XIII

R^(f)—NC  (XIII)

under such conditions that compound X is formed,

wherein R^(d) represents a hydrogen atom, a substituted or unsubstitutedalkyl, alkenyl, alkynyl, aromatic or non-aromatic, mono-, di-polycyclicor alkylcycloalkyl, or a heterocyclic structure,

R^(e) represents a substituted or unsubstituted alkyl, alkenyl, alkynyl,aromatic or non-aromatic, mono-, di- or tricyclic, or heterocyclicstructure, and

R^(f) represents a hydrogen atom, a substituted or unsubstituted alkyl,alkenyl, or alkynyl structure.

Preferably, compound XIII thus obtained is subsequently isolated fromthe reaction mixture.

R^(d) preferably represents a hydrogen, a straight chain alkyl, abranched chain alkyl, a cycloalkyl, an alkylene-cycloalkyl, an aryl,alkylene-aryl, SO₂-alkyl, SO₂-aryl, alkylene-SO₂-aryl,-alkylene-SO₂-alkyl, heterocyclyl or alkylene-heterocyclyl; CH₂CO—X—H,—CH₂CO—X-straight chain alkyl, —CH₂CO—X-branched chain alkyl,—CH₂CO—X-cycloalkyl, —CH₂CO—X-alkylene-cycloalkyl, —CH₂CO—X-aryl,—CH₂CO—X-alkylene-aryl, —CH₂CO—X-heterocyclyl,—CH₂CO—X-alkylene-heterocyclyl or —CH₂CO-aryl; wherein X represents O orNH.

R^(e) preferably represents hydrogen, a straight chain alkyl, a branchedchain alkyl, a cycloalkyl, an alkylene-cycloalkyl, an aryl, and/oralkylene-aryl.

R^(f) preferably represents hydrogen, a straight chain alkyl, a branchedchain alkyl, a cycloalkyl, an alkylene-cycloalkyl, an aryl, and/oralkylene-aryl.

In the present invention, the substituents R^(d) to R^(f) according togeneral formula (I) are defined as follows:

In a preferred embodiment of the subject invention, R^(d) represents analkyl group such as ethyl, or an alkylcycloalkyl group, such asethylcyclopropyl or ethlycyclobutyl.

R^(e) preferably is an acetate group, and R^(f) preferably is acyclopropyl group. The process according to the present inventionfurther advantageously comprises a step c) of subjecting compound X todehydrating conditions to obtain an isocyanate compound according togeneral formula IX as set out herein above.

This may advantageously be achieved for instance by treatment of theformamido compound (X) with phosgene, diphosgene(trichloromethylchloroformate) and/or triphosgene [bis(trichloromethyl)carbonate], under suitable conditions as known to a skilled person.

Preferably, the aldehyde according to formula XI is derived from anoptionally substantially enantiomerically pure 2-substituted2-amino-1-ethanol according to general formula XIV

wherein R¹ represents R^(d) as defined herein above.

The aldehyde compound XI may advantageously be prepared from ansubstituted 2-amino-1-ethanol according to general formula XIV by A)N-formylation, and B) by a selective oxidation of the primary alcohol ofthe obtained N-formylated alcohol intermediate to an aldehyde.

This oxidation is advantageously performed by employing a Dess-Martinoxidation. In this way, the stereogenic centre and various substituentsR^(d) can be introduced from often commercially or synthetically readilyavailable 2-aminoethanols. A so-called Dess-Martin oxidation employs theDess-Martin Periodinane (DMP), a hypervalent iodine compound for theselective and very mild oxidation of alcohols to aldehydes or ketones,as disclosed for instance in Y. Yip, F. Victor, J. Lamar, R. Johnson, Q.M. Wang, J. I. Glass, N. Yumibe, M. Wakulchik, J. Munroe, S.-H Chen,Bioorg. Med. Chem. Lett. 2004, 14, 5007-5011.

The oxidation preferably may be performed in dichloromethane orchloroform at room temperature, and is usually complete within 0.5-2hours. Products are easily separated from the iodo-compound by-productafter basic work-up.

Preferably, the Dess-Martin oxidation according to the invention isperformed in the presence of compound IV, in such a way that thealdehyde II that is formed during the Dess-Martin oxidation immediatelyreacts in a Passerini reaction with the acetic acid that is formed as aby-product of the Dess-Martin oxidation as carboxylic acid III andisocyanide IV. This has the tremendous benefit that the atomicefficiency of the reaction is increased, since the Dess-MartinPeriodinane (DMP) also provides a reactant for the second stage of thereaction, i.e., the Passerini three-component reaction. In addition, thecombination of two reaction steps in one pot is advantageous in terms ofboth time and resources (less solvent and manpower required, one workupand chromatography less, etc.).

In a preferred embodiment of the subject process, the compound accordingto formula V

is reacted with a compound according to general formula XV:

and a compound according to general formula XVI:

Under conditions that allow formation of a compound according to formulaXVII:

After the reaction, compound XVII could be advantageously isolated fromthe reaction mixture.

The subject process further preferably comprises subjecting the compoundaccording to formula XVII to a saponification reaction to remove theacetate from the secondary alcohol at the α-hydroxy-β-amino acidstructure.

The saponification preferably is carried out by contacting the compoundaccording to formula XVII with a alkaline metal carbonate, preferablyK₂CO₃ in a suitable solvent, to obtain a saponified alcohol productaccording to formula XIIa.

The released intermediate compound comprising the secondary alcohol isthe subjected to a selective oxidation of the secondary alcohol to formcompound XVIII,

This compound, which also known as Telaprevir, could be prepared inhigher yields and with higher efficiency than any previously disclosedprocesses. Furthermore, the chiral information used for the preparationwas derived from readily available simple building blocks, making theprocess a highly effective approach to such prolyl dipeptides andsimilar peptidomimetics.

In a further preferred embodiment of the subject process, a compoundaccording to general formula VII as defined herein above is reacted withan acid compound according to general formula XVII:

and an isocyanide compound according to general formula XX:

to obtain a compound according to general formula XXI

which may advantageously be saponified to a secondary alcohol andsubsequently oxidized to a ketone, thereby yielding, after removal undersuitable conditions of the R² group, a compound according to formulaXXII:

also known as Boceprevir.

The process according to the present invention advantageously permits toselectively produce the two diastereomers according to the generalformula XXIIa:

and according to the general formula XXIIb, respectively,

The subject invention therefore also relates to a process wherein XXIIaor XXIIb are selectively prepared, and to the thus obtained compoundsXXIIa or XXIIb.

Suitable solvents for the subject reaction are polar protic and aproticorganic solvents, including methanol, ethanol, 2-propanol and otheralcohol solvent, tetrahydrofuran, 1,4-dioxane, acetonitrile, and/ormixtures of these solvents with water or less polar organic solvents,such as dichloromethane or chloroform.

The saponification or removal of the ester group through hydrolysis maybe performed by any suitable method known to a skilled person.Preferably, it is carried out by contacting the obtained reactionproduct according to formula I with an alkaline metal carbonate, morepreferably K₂CO₃ in a suitable solvent, to obtain a saponified alcoholproduct. The saponified alcohol product may then advantageously beoxidised selectively at the secondary alcohol function, preferablywithout affecting the other structures on the compound, to yield aketone compound.

The selective oxidation is preferably carried out by contacting thesaponified alcohol product with a suitable oxidant in a suitablesolvent. Suitable solvents include dichloromethane, THF, ethyl acetate,DMSO. Suitable oxidants include hypervalent iodine reagents such as IBX,Dess-Martin periodinane, etc., or a combination of TEMPO and PhI(OAc)₂or related reagents.

The compounds obtainable by the subject process may furtheradvantageously be used as (asymmetric) organocatalysts for the additionof enolizable aldehydes to electrophiles such as (among others)nitroalkenes, α,β-unsaturated carbonyl compounds (aldehydes, esters,amides), vinyl sulfones, and the like. The subject invention alsoadvantageously relates to compounds XVII, XVIIa, XXIIa and XXIIb, asccurucal building blocks for prolyl dipeptides.

EXPERIMENTAL SECTION

The following non-limiting experiments illustrate the process accordingto the subject invention.

General Information

Starting materials and solvents were purchased from ABCR andSigma-Aldrich and were used without treatment. 3-Azabicylo[3,3,0]octanehydrochloride was purchased from AK Scientific.(1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene wasprepared according to literature procedure.¹ Column chromatography wasperformed on silica gel. ¹H and ¹³C NMR spectra were recorded on aBruker Avance 400 (400.13 MHz for ¹H and 100.61 MHz for ¹³C) or BrukerAvance 500 (500.23 MHz for ¹H and 125.78 MHz for ¹³C) in CDCl₃ andDMSO-d₆. Chemical shifts are reported in 6 values (ppm) downfield fromtetramethylsilane.

Electrospray Ionization (ESI) mass spectrometry was carried out using aBruker micrOTOF-Q instrument in positive ion mode (capillary potentialof 4500 V). GC-MS spectra were recorded on a Hewlett Packard HP 6890equipped with a J & W Scientific; HP-1MS; 30 m×0.32 mm×0.25 μm column(injector temp. 300° C., oven temp. 100° C. to 280° C. at 5° C./min,hold for 10 min., He 1.6 ml/min. and detector temp. 275° C.) and a HP5973 Mass Selective Detector. GC-FID analyses were performed on Agilent6850 GC with a J & W Scientific; HP-1; 30 m×0.32 mm×0.25 μm (injectortemp. 300° C., oven temp. 100° C. to 280° C. at 5° C./min, hold for 10min., He 1.6 ml/min. and detector temp. 275° C.) and a VarianChirasil-Dex CB; 25 m×0.25 mm×0.26 μm column (inj. 250° C., oven temp.100° C. to 180° C. at 5° C./min, hold for 10 min., He 1.6 ml/min. anddetector temp. 275° C.) equipped with a Gerstel Multipurpose samplerMPS2L. Normal phase HPLC was performed on Agilent systems. Normal phaseHPLC system was equipped with a G1322A degasser, a G1311A quaternarypump, a G1329 autosampler unit, a G1315B diode array detector and aG1316A temperature controlled column compartment. Infrared (IR) spectrawere recorded neat, and wavelengths are reported in cm⁻¹. Opticalrotations were measured with a sodium lamp and are reported as follows:[α]_(D) ²⁰ (c=g/100 mL, solvent). Methyl 3-isocyanopropionate wassynthesized as reported previously.³

General Procedure 1: Preparation of Optically Active Imines (3S,7R)-4and 6.

Unless stated otherwise: imines were synthesised according to literatureprocedure² with minor adjustments. 2.5 g of freeze-dried MAO-N D5 E.Coli were rehydrated for 30 min. in 20 ml of KPO₄ buffer (100 mM,pH=8.0) at 37° C. Subsequently 1 mmol amine ((3S,7R)-4 or 6) in 30 ml ofKPO₄ buffer (100 mM, pH=8.0) was prepared.

The pH of the solution was adjusted to 8.0 by addition of NaOH and thenadded to the rehydrated cells. After 16-17 h The reaction was stopped(conversions were >95%) and worked up. For workup the reaction mixturewas centrifuged at 4000 rpm and 4° C. until the supernatant hadclarified (40-60 min.). The pH of the supernatant was then adjusted to10-11 by addition of aq. NaOH and the supernatant was subsequentlyextracted with t-butyl methyl ether or dichloromethane (4×70 mL). Thecombined organic phases were dried with Na₂SO₄ and concentrated at therotary evaporator.

General Procedure 2: Preparation of Optically Active Ugi-Type Products5a-g & 7a-g

Unless stated otherwise: Imine (0.70 mmol) was dissolved in 2 ml ofCH₂Cl₂ followed by the addition of carboxylic acid (0.93 mmol) andisocyanide (0.93 mmol). The reaction mixture was stirred for 24 h at RT.CH₂Cl₂ (8 mL) was added and the resulting mixture was washed with Na₂CO₃(2×10 mL), dried (MgSO₄), filtered, and concentrated. Note: rotamerscould be observed in the NMR data.

General Procedure 3: Determination of Enantiomeric Excess (ee) andDiastereomeric Ratio (d.r.)

Racemic imines were synthesised according to literature procedure².Racemic Ugi-type products were prepared according to general procedure3. Diastereomers could be separated by GC-MS and GC-FID. Enantiomerscould be separated by normal phase HPLC and GC-FID.

Example 1

Compound 5a:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), acetic acid (55 mg, 52 μl, 0.91 mmol) andt-butyl isocyanide (76 mg, 103 μl, 0.91 mmol) giving 5a as a whitesolid, yield 73%.

93:7 d.r. [HP-1, t (major)=14.852 min, t (minor)=16.773 min]; 95% ee [CPChirasil-DEX CB, t (minor)=20.449 min, t (major)=20.860 min]; [α]_(D)²⁰=−47.8° (c=0.34, MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 6.58 (bs, 1H),4.28 (d, J=2.1 Hz, 1H), 3.70 (dd, J=8.3, 10.6 Hz, 1H), 3.24 (dd, J=4.5,10.6 Hz, 1H), 2.96-2.93 (m, 1H), 2.91-2.82 (m, 1H), 2.01 (s, 3H),1.93-1.78 (m, 2H), 1.71-1.42 (m, 2H), 1.41-1.31 (m, 2H), 1.25 (s, 9H);¹³C NMR (100.6 MHz, CDCl₃) δ 170.5, 170.0, 66.8, 54.4, 51.0, 45.0, 42.7,32.5, 32.3, 28.7, 25.7, 22.6; IR (neat): ν_(max) (cm⁻¹)=3277 (m), 2957(m), 1668 (s), 1630 (s), 1549 (s), 1447 (s), 1420 (s), 1223 (s), 667(m), 606 (m); HRMS (ESI+) calcd for C₁₄H₂₄N₂O₂ ([M+H]⁺) 253.1916. found253.1925.

Example 2

Compound 5b:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), benzoic acid (111 mg, 0.91 mmol) andt-butyl isocyanide (76 mg, 103 μl, 0.91 mmol) giving 5b as a whitesolid, yield 73%.

93:7 d.r. [HP-1, t (major)=23.672 min, t (minor)=25.601 min]; 95% ee[Daicel Chiralpak AD-H, hexane/2-propanol=96/4, v=1.0 mL/min¹, λ=254 nm,t (minor)=10.698 min, t (major)=11.620 min]; [α]_(D) ²⁰=−53.7° (c=0.34,MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.49-7.38 (m, 5H), 6.66 (bs, 1H),4.54 (d, J=2.8 Hz), 3.72 (dd, J=11.4, 7.8 Hz, 1H), 3.23 (d, J=11.0, 1H),3.15-3.10 (m, 1H), 2.73-2.58 (m, 1H), 1.96-1.82 (m, 1H), 1.82-1.69 (m,1H), 1.68-1.41 (m, 3H), 3.15-3.10 (m, 1H), 1.28 (s, 9H), 1.24-1.06 (m,1H); ¹³C NMR (100.6 MHz, CDCl₃) δ170.3, 170.1, 136.3, 130.1, 128.4,126.9, 67.1, 60.4, 55.9, 51.1, 44.2, 43.3, 33.0, 32.7, 28.7, 26.2; IR(neat): ν_(max) (cm⁻¹)=3310 (m), 2961 (m), 1674 (s), 1618 (s), 1416 (s),1223 (s), 698 (s); HRMS (ESI+) calcd for C₁₉H₂₆N₂O₂ ([M+H]⁺) 315.2073.found 315.2077.

Example 3

Compound 5c:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), 3-furoic acid (102 mg, 0.91 mmol) andisopropyl isocyanide (63 mg, 86 μl, 0.91 mmol) giving 5c as a whitesolid, yield 75%.

92:8 d.r. [HP-1, t (major)=21.290 min, t (minor)=23.012 min] 94% ee[Daicel Chiralpak AD-H, hexane/2-propanol=90/10, v=1.0 mL·min¹, λ=254nm, t (minor)=7.417 min, t (major)=12.039 min]; [α]_(D) ²⁰=−33.3°(c=0.30, MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.80 (bs, 1H), 7.43 (bs,1H), 6.72 (bs, 1H), 6.51 (d, J=6.3 Hz, 1H), 4.56 (d, J=2.3 Hz, 1H), 4.03(oct, J=7.1 1H), 3.88 (dd, J=10.4, 8.3 Hz, 1H), 3.53 (dd, J=10.4, 3.8Hz, 1H), 3.09-3.01 (m, 1H), 2.95-2.84 (m, 1H), 2.00-1.84 (m, 2H),1.74-1.65 (m, 1H), 1.64-1.54 (m, 1H), 1.53-1.43 (m, 1H), 1.43-1.33 (m,1H), 1.17 (d, J=6.3 Hz, 3H) 1.13 (d, J=6.3 Hz, 3H); ¹³C NMR (100.6 MHz,CDCl₃) δ 170.1, 163.2, 144.3, 142.8, 121.8, 110.4, 66.8, 54.8, 44.4,43.3, 41.3, 32.4, 32.2, 25.6, 22.5, 22.4; IR (neat): ν_(max)(cm⁻¹)=3281(w), 2949 (w), 1647 (m), 1609 (s), 1547 (s), 1427 (s), 1159 (s), 737(s), 598 (s); HRMS (ESI+) calcd for C₁₆H₂₂N₂O₃ ([M+H]⁺) 291.1709. found291.1721.

Example 4

Compound 5d:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), benzoic acid (111 mg, 0.91 mmol) andisopropyl isocyanide (63 mg, 86 μl, 0.91 mmol) giving 5d as a whitesolid, yield 78%.

92:8 d.r. [HP-1, t (major)=23.809 min, t (minor)=25.563 min]; 94% ee[Daicel Chiralpak AD-H, hexane/2-propanol=96/4, v=1.0 mL/min¹, λ=254 nm,t (minor)=16.613 min, t (major)=21.363 min]; [α]_(D) ²⁰=−52.4° (c=0.42,MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.46-7.36 (m, 1H), 6.63 (bs, 1H),4.59 (d, J=2.0 Hz, 1H), 4.10-4.01 (m, 1H), 3.73 (dd, J=11.4, 7.8 Hz,1H), 3.73 (dd, J=11.4, 7.8 Hz, 1H), 3.32-3.29 (m, 1H), 3.23-3.17 (m,1H), 2.76-2.71 (m, 1H), 2.02-1.94 (m, 1H), 1.88-1.78 (m, 1H), 1.75-1.63(m, 1H), 1.63-1.50 (m, 1H), 1.16 (d, J=6.6 Hz, 3H) 1.13 (d, J=6.6 Hz,3H); ¹³C NMR (100.6 MHz, CDCl₃) δ 170.4, 170.0, 136.2, 130.1, 128.4,126.9, 126.6, 66.5, 55.9, 44.3, 43.3, 41.5, 32.9, 32.6, 26.1, 22.7,22.6; IR (neat): ν_(max)(cm⁻¹)=3300 (m), 2959 (m), 1615 (s), 1545 (s),1416 (s), 1229 (m), 700 (m); HRMS (ESI+) calcd for C₁₈H₂₄N₂O₂ ([M+H]⁺)301.1916. found 301.1914.

Example 6

Compound 5e:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), acetic acid (55 mg, 52 μl, 0.91 mmol) andbenzyl isocyanide (107 mg, 111 μl, 0.91 mmol) giving 5e as a whitesolid, yield 71%.

92:8 d.r. [HP-1, t (major)=25.098 min, t (minor)=26.457 min]; 94% ee[Daicel Chiralpak OJ-H, hexane/2-propanol=93/7, v=1.0 mL·min¹, λ=254 nm,t (minor)=9.948 min, t (major)=10.718 min]; [α]_(D) ²⁰=−18.8° (c=0.32,MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.36-7.25 (m, 5H), 7.16 (bs, 1H),4.47 (d, J=2.0 Hz, 1H), 4.25 (dd, J=15.2, 5.8 Hz, 2H), 3.73 (dd, J=10.6,8.3 Hz, 1H), 3.28 (dd, J=10.5, 4.5 Hz, 1H), 3.10-3.03 (m, 1H), 2.96-2.88(m, 1H), 2.10 (s, 3H), 2.01-1.85 (m, 1H), 1.82-1.55 (m, 2H), 1.52-1.39(m, 2H); ¹³C NMR (100.6 MHz, CDCl₃) δ 171.3, 170.1, 138.3, 128.5, 128.4,127.9, 127.4, 127.0, 65.9, 54.3, 45.4, 43.2, 42.7, 32.6, 32.2, 25.5,22.1; IR (neat): ν_(max)(cm⁻¹)=3267 (m), 2951 (w), 1626 (s), 1537 (m),1418 (s), 1231 (s), 1030 (w), 748 (s); HRMS (ESI+) calcd for C₁₇H₂₂N₂O₂([M+H]⁺) 287.1760. found 281.1765.

Example 7

Compound 5f:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), benzoic acid (111 mg, 0.91 mmol) andbenzyl isocyanide (107 mg, 111 μl, 0.91 mmol) giving 5f as a whitesolid, yield 81%.

92:8 d.r. [HP-1, t (major)=33.333 min, t (minor)=35.085 min]; 97% ee[Daicel Chiralpak AD-H, hexane/2-propanol=96/4, v=1.0 mL/min¹, λ=254 nm,t (minor)=18.134 min, t (major)=23.440 min]; [α]_(D) ²⁰=−52.6° (c=0.38,MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.34-7.11 (m, 10H), 6.73 (bs, 1H),4.61 (d, J=2.8 Hz, 1H). 4.37 (dd, J=5.3, 2.8 Hz, 2H), 3.66 (dd, J=11.1,7.6 Hz, 1H), 3.24 (dd, J=10.9, 1.8 Hz, 1H), 3.18-3.11 (m, 1H), 2.72-2.64(m, 1H), 1.92-1.82 (m, 1H), 1.82-1.62 (m, 1H), 1.25-1.13 (m, 1H); ¹³CNMR (100.6 MHz, CDCl₃) δ171.1, 170.3, 138.3, 135.9, 132.6, 130.0, 129.7,128.4, 128.21, 128.0, 127.7, 127.3, 127.0, 126.9, 126.4, 66.3, 55.8,44.9, 43.2, 43.1, 32.8, 32.4, 25.9; IR (neat): ν_(max)(cm⁻¹)=3262 (m),2928 (m), 1674 (s), 1613 (s), 1545 (s), 1423 (s), 1223 (m), 698 (s), 669(s); HRMS (ESI+) calcd for C₂₂H₂₄N₂O₂ ([M+H]⁺) 349.1916. found 349.1924.

Example 8

Compound 5g:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene((3S,7R)-4, 76 mg, 0.70 mmol), isobutyric acid (80 mg, 84 μl, 0.91 mmol)and t-butyl isocyanide (76 mg, 103 μl, 0.91 mmol) giving 5g as a whitesolid, yield 83%.

93:7 d.r. [HP-1, t (major)=17.165 min, t (minor)=18.750 min]; 97% ee [CPChirasil-DEX CB, t (minor)=21.439 min, t (major)=21.846 min]; [α]_(D)²⁰=−47.8° (c=0.34, MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 6.71 (bs, 1H),4.37 (d, J=1.8 Hz, 1H), 3.65 (dd, J=10.6, 8.3 Hz, 1H), 3.34 (dd, J=4.3,10.9 Hz, 1H), 3.04-2.98 (m, 1H), 2.89-2.81 (m, 1H), 2.65 (sep, J=6.8 Hz,1H), 2.01-1.83 (m, 2H), 1.70-1.48 (m, 2H), 1.45-1.35 (m, 2H), 1.29 (s,9H), 1.13 (d, J=6.6 Hz, 3H), 1.10 (d, J=6.8 Hz, 3H); ¹³C NMR (100.6 MHz,CDCl₃) δ176.5, 170.4, 66.5, 53.0, 43.7, 42.7, 32.8, 32.3, 32.0, 30.8,24.9, 18.9, 18.5; IR (neat): ν_(max) (cm⁻¹)=3291 (m), 2963 (m), 2870(w), 1684 (s), 1618 (s), 1551 (s), 1433 (s), 1225 (s), 1090 (m), 658(m); HRMS (ESI+) calcd for C₁₄H₂₄N₂O₂ ([M+H]⁺) 281.2229. found 281.2235.

Example 9

Compound 7a:

General procedure 2 was followed using(1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), acetic acid (55 mg, 52 μl, 0.91 mmol) and t-butyl isocyanide(76 mg, 103 μl, 0.91 mmol) giving 7a as a white solid, yield 83%.

>99:1 d.r. (t (major)=18.179 min); >99% ee [Daicel Chiralpak AD-H,hexane/2-propanol=92/8, v=1.0 mL·min¹, λ=220 nm, t (major)=5.319 min, t(minor)=6.587 min]; [α]_(D) ²⁰=−24.0° (c=0.25, MeCN). ¹H NMR (400.1 MHz,CDCl₃): δ 6.65 (bs, 1H), 6.14-6.13 (m, 2H), 4.09 (d, J=2.0 Hz, 1H), 3.47(dd, J=11.4, 8.6 Hz, 1H), 3.36-3.32 (m, 1H), 3.15 (dd, J=11.4, 2.0 Hz,1H), 2.98-2.92 (m, 3H), 1.95 (s, 3H), 1.51-1.41 (m, 2H), 1.30 (s, 9H);¹³C NMR (100.6 MHz, CDCl₃) δ170.6, 169.0, 135.4, 134.0, 62.9, 51.7,51.0, 50.3, 47.0, 46.6, 46.0, 45.1, 28.7, 22.8; IR (neat):ν_(max)(cm⁻¹)=3283 (w), 2970 (w), 2942 (w), 1647 (s), 1634 (s), 1553(s), 1414 (s), 1223 (s), 733 (s); HRMS (ESI+) calcd for C₁₆H₂₄N₂O₂([M+H]⁺) 277.1916. found 277.1922.

Example 10

Compound 7b:

General procedure 2 was followed using 3-azabicyclo[3,3,0]oct-2-ene (6,76 mg, 0.70 mmol), benzoic acid (111 mg, 0.91 mmol) and t-butylisocyanide (76 mg, 103 μl, 0.91 mmol) giving 7b as a white solid, yield82%.

>99:1 d.r. (t (major)=26.830 min); HP-1, >99% ee [Daicel Chiralpak AD-H,hexane/2-propanol=96/4, v=1.0 mL·min¹, λ=220 nm, t (minor)=9.712 min, t(major)=11.741 min]; [α]_(D) ²⁰=−43.1° (c=0.33, MeCN). ¹H NMR (400.1MHz, CDCl₃): δ 7.43-7.34 (m, 1H), 6.63 (bs, 1H), 6.20 (dd, J=5.8, 3.0Hz, 1H), 5.91 (dd, J=5.6, 2.6 Hz, 1H), 4.43 (d, J=2.0 Hz, 1H), 3.52 (dd,J=11.9, 8.6 Hz, 1H), 3.44-3.39 (m, 1H), 3.05-3.00 (m, 2H), 2.91-2.85 (m,1H), 2.78-2.76 (m, 1H), 1.48-1.45 (m, 1H), 1.40-1.37 (m, 1H), 1.32 (s,9H); ¹³C NMR (100.6 MHz, CDCl₃) δ168.6, 168.0, 135.0, 133.2, 132.7,128.4, 126.8, 124.9, 61.3, 50.4, 49.9, 49.5, 45.4, 44.9, 43.9, 43.3,27.1; IR (neat): ν_(max)(cm⁻¹)=3283 (m), 2970 (m), 2942 (m0, 1647 (s),1634 (s), 1553 (s), 1414 (s), 1223 (s), 733 (s); HRMS (ESI+) calcd forC₂₁H₂₆N₂O₂ ([M+H]⁺) 339.2073. found 339.2082.

Example 11

Compound 7c:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), 3-furoic acid (102 mg, 0.91 mmol) and isopropyl isocyanide(63 mg, 86 μl, 0.91 mmol) giving 7c as a white solid, yield 75%.

>99:1 d.r. (t (major)=24.364 min); >99% ee [Daicel Chiralpak AD-H,hexane/2-propanol=90/10, v=1.0 mL·min¹, λ=220 nm, t (minor)=8.404 min, t(major)=9.968 min]; [α]_(D) ²⁰=−35.7° (c=0.28, MeCN). ¹H NMR (400.1 MHz,CDCl₃): δ 7.71 (dd, J=1.5, 0.8 Hz, 1H), 7.42 (dd, J=2.0, 1.5 Hz, 1H),6.65 (dd, J=1.8, 0.8 Hz, 1H), 6.50 (d, J=6.6 Hz, 1H), 6.19-6.17 (m, 1H),5.98-5.96 (m, 1H), 4.42 (d, J=2.0 Hz, 1H), 4.06-3.94 (m, 1H), 3.63 (dd,J=11.4, 8.8 Hz, 1H), 3.43-3.39 (m, 2H), 3-06-3.02 (m, 2H), 2.90-2.88 (m,1H), 1.51-1.43 (m, 2H), 1.13 (d, J=6.6 Hz, 3H), 1.10 (d, J=6.6 Hz, 3H);¹³C NMR (100.6 MHz, CDCl₃) δ 170.2, 162.7, 144.1, 142.9, 135.1, 134.4,121.9, 110.4, 62.8, 51.6, 51.2, 47.1, 46.5, 45.8, 45.2, 41.5, 22.6,22.7, 22.6; IR (neat): ν_(max)(cm⁻¹)=3275 (m), 2970 (m), 2934 (m), 1678(s), 1594 (s), 1545 (s), 1437 (s), 1219 (s), 1153 (m), 1018 (m) 874 (m0,754 (s); HRMS (ESI+) calcd for C₁₈H₂₂N₂O₂ ([M+H]⁺) 315.1709. found315.1725.

Example 12

Compound 7d:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), benzoic acid (111 mg, 0.91 mmol) and isopropyl isocyanide(63 mg, 86 μl, 0.91 mmol) giving 7d as a white solid, yield 78%.

>99:1 d.r. (t (major)=27.054 min); >99% ee [Daicel Chiralpak AD-H,hexane/2-propanol=96/4, v=1.0 mL·min¹, λ=220 nm, t (minor)=17.354 min, t(major)=29.404 min]; [α]_(D) ²⁰=−38.7° (c=0.31, MeCN). ¹H NMR (400.1MHz, CDCl₃): δ 7.43-7.35 (m, 5H), 6.59 (d, J=7.6 Hz, 1H), 6.23-6.21 (m,1H), 5.93-5.91 (m, 1H), 4.48 (d, J=1.7 Hz, 1H), 4.11-3.98 (m, 1H), 3.55(dd, J=11.9, 8.8 Hz, 1H), 3.48-3.45 (m, 1H), 3.07-3.00 (m, 2H),2.92-2.87 (m, 1H), 2.81-2.77 (m, 1H), 1.48-1.39 (m, 2H), 1.14 (d, J=6.6Hz, 3H), 1.10 (d, J=6.6 Hz, 3H); ¹³C NMR (100.6 MHz, CDCl₃) δ 170.1,169.8, 136.5, 134.8, 134.4, 130.1, 128.4, 126.6, 62.3, 52.0, 51.5, 47.0,46.5, 45.6, 44.9, 41.5, 22.7, 22.6; IR (neat): ν_(max)(cm⁻¹)=3287 (m),2967 (m), 2940 (m), 1682 (s), 1601 (s), 1539 (s), 1424 (s), 1217 (s),739 (s), 664 (m); HRMS (ESI+) calcd for C₂₀H₂₄N₂O₂ ([M+H]⁺) 325.1916.found 325.1919.

Example 13

Compound 7e:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), acetic acid (55 mg, 52 μl, 0.91 mmol) and benzyl isocyanide(107 mg, 111 μl, 0.91 mmol) giving 7e as a white solid, yield 78%.

>99:1 d.r. (t (major)=28.213 min); >99% ee [Daicel Chiralpak OJ-H,hexane/2-propanol=92/8, v=1.0 mL·min¹, λ=220 nm, t (minor)=9.100 min, t(major)=10.760 min]; [α]_(D) ²⁰=−21.4° (c=0.28, MeCN). ¹H NMR (400.1MHz, CDCl₃): δ 7.31-7.21 (m, 5H), 6.13-6.08 (m, 2H), 4.46 (dd, J=14.9,6.1 Hz, 1H), 4.32 (dd, J=15.2, 5.8 Hz, 1H), 4.25 (d. J=2.0 Hz, 1H),3.47-3.43 (m, 2H), 3.18 (dd, J=11.4, 2.0 Hz, 1H), 3.01-2.95 (m, 3H), 2.0(s, 3H), 1.54-1.43 (m, 2H); ¹³C NMR (100.6 MHz, CDCl₃) 171.3, 169.3,138.3, 135.4, 134.1, 128.6, 127.4, 127.3, 62.2, 51.7, 50.3, 47.1, 46.7,46.0, 45.1, 43.4, 22.7; IR (neat): ν_(max)(cm⁻¹)=3314 (w), 3082 (w),2970 (w), 2932 (w), 1553 (s), 1433 (s), 1360 (m), 1317 (m), 1233 (m),745 (s), 696 (s); HRMS (ESI+) calcd for C₁₉H₂₂N₂O₂ ([M+H]⁺) 311.1760.found 311.1745.

Example 14

Compound 7f:

General procedure 2 was followed using31R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), benzoic acid (111 mg, 0.91 mmol) and benzyl isocyanide (107mg, 111 μl, 0.91 mmol) giving 7f as a white solid, yield 80%.

>99:1 d.r. (t (major)=36.331 min); >99% ee [Daicel Chiralpak OD-H,hexane/2-propanol=92/8, v=1.0 mL·min¹, λ=220 nm, t (major)=11.489 min, t(minor)=13.626 min]; [α]_(D) ²⁰=−35.1° (c=0.29, MeCN). ¹H NMR (400.1MHz, CDCl₃): δ 7.44-7.17 (m, 10H), 6.24-6.18 (m, 1H), 5.95-5.93 (m, 1H),4.60 (d, J=1.8 Hz, 1H), 4.45 (d, J=5.8 Hz, 2H), 3.58-3.50 (m, 2H),3.10-3.04 (m, 2H), 2.95-2.89 (m, 1H), 2.83-2.79 (m, 1H), 1.50-1.41 (m,2H); ¹³C NMR (100.6 MHz, CDCl₃) δ 171.1, 169.9, 138.4, 136.4, 134.4,130.1, 128.6, 128.4, 127.4, 127.3, 126.4, 62.2, 52.1, 51.6, 47.0, 46.6,45.6, 45.0, 43.5; IR (neat): ν_(max) (cm⁻¹)=3268 (m), 3077 (w), 2972(w), 2872 (w), 1684 (s), 1597 (s), 1560 (s), 1495 (m), 1431 (s), 1221(s), 731 (s), 696 (s); HRMS (ESI+) calcd for C₂₄H₂₄N₂O₂ ([M+H]⁺)373.1916. found 373.1901.

Example 15

Compound 7g:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), isobutyric acid (80 mg, 84 μl, 0.91 mmol) and t-butylisocyanide (76 mg, 103 μl, 0.91 mmol) giving 7g as a white solid, yield81%.

>99:1 d.r. (t (major)=19.912 min); >99% ee [Daicel Chiralpak AD-H,hexane/2-propanol=95/5, v=1.0 mL·min¹, λ=220 nm, t (minor)=5.037 min, t(major)=6.877 min]; [α]_(D) ²⁰=−35.3° (c=0.34, MeCN). ¹H NMR (400.1 MHz,CDCl₃): δ 6.13-6.08 (m, 2H), 4.15 (d, J=1.8 Hz, 1H), 3.43 (dd, J=11.4,8.6 Hz, 1H), 3.37-3.33 (m, 1H), 3.26 (dd, J=11.4, 2.0 Hz, 1H), 2.99-2.91(m, 3H), 2.50 (sep, J=6.8 Hz, 1H), 1.54-1.38 (m, 2H), 1.27 (s, 9H), 1.06(d, J=6.8 Hz, 3H), 1.03 (d, J=6.8 Hz, 3H); ¹³C NMR (100.6 MHz, CDCl₃) δ175.6, 170.7, 135.3, 134.2, 62.7, 51.8, 50.8, 49.1, 47.01, 46.5, 45.2,32.2, 28.7, 19.2, 18.3; IR (neat): ν_(max) (cm⁻¹)=3325 (m), 2966 (m),1678 (m), 1624 (s), 1553 (s), 1435 (s), 1315 (w), 1231 (m), 1088 (w);HRMS (ESI+) calcd for C₁₈H₂₈N₂O₂ ([M+H]⁺) 305.2229. found 305.2224.

Example 16

Compound 8a:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), Fmoc-D-Pro-OH (307 mg, 0.91 mmol) and t-butyl isocyanide (76mg, 103 μl, 0.91 mmol). The crude product 8 was subjected using columnchromatography (SiO₂, EtOAc (1): cyclohexane (2)). Fmoc deprotectionusing 25% piperidine in DMF followed by column chromatography(CH₂Cl₂/MeOH 9:1) gave 8a as a white solid in 66% yield over two steps.[α]_(D) ²⁰=−75.0° (c=0.16, MeCN). ¹H NMR (500.2 MHz, CDCl₃): δ 6.75 (bs,1H), 6.11 (d, J=5.7 Hz, 2H), 5.01 (bs, 1H), 4.20 (bs, 1H), 3.92-3.83 (m,1H), 3.45-3.41 (m, 1H), 3.24-3.22 (m, 1H), 3.20-3.10 (m, 2H), 3.03-2.98(m, 2H), 2.95-2.89 (m, 1H), 2.19-2.09 (m, 1H), 1.94-1.57 (m, 3H),1.57-1.39 (m, 2H), 1.28 (s, 9H); ¹³C NMR (125.8 MHz, CDCl₃) δ 170.5,135.4, 134.4, 63.7, 61.4, 51.6, 51.0, 49.01, 47.2, 46.9, 46.5, 46.3,45.4, 30.0, 28.7, 25.9; IR (neat): ν_(max) (cm⁻¹)=2960 (w), 1668 (s),1622 (s), 1566 (m), 1414 (s), 1234 (m), 1094 (w), 853 (s); HRMS (ESI+)calcd for C₁₉H₂₉N₃O₂ ([M+H]⁺) 332.2338. found 332.2342.

Example 18

Compound 9:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), Fmoc-L-Pro-OH (307 mg, 0.91 mmol) and t-butyl isocyanide (76mg, 103 μl, 0.91 mmol) giving 9 as a white solid, yield 76%.

[α]_(D) ²⁰=−6.7° (c=0.60, MeCN). ¹H NMR (500.2 MHz, CDCl₃): δ 7.76 (d,J=7.6 Hz, 2H), δ 7.59 (d, J=7.5 Hz, 1H), 7.55 (d, J=7.5 Hz, 1H), 7.40(d, J=7.4 Hz, 2H), 7.40 (d, J=7.4 Hz, 2H), 7.31 (d, J=7.4 Hz, 2H),),6.62 (bs, 1H), 6.19 (dd, J=5.6, 2.9 Hz, 1H), 6.11 (dd, J=5.6, 2.5 Hz,1H), 4.35-4.33 (m, 1H), 4.30-4.28 (m, 2H), 4.24-4.22 (m, 1H), 4.20 (d,J=1.9 Hz, 1H), 3.72-3.58 (m, 2H), 3.35-3.32 (m, 1H), 3.25-3.22 (m, 2H),2.93-2.90 (m, 2H), 2.18-2.13 (m, 2H), 1.95-1.91 (m, 2H), 1.52-1.40 (m,2H), 1.29 (s, 9H);); ¹³C NMR (125.8 MHz, CDCl₃) δ 170.6, 170.4, 154.8,143.9, 141.3, 135.9, 134.2, 127.8, 127.7, 127.1, 127.0, 125.1, 125.0,120.0, 67.5, 63.3, 58.3, 51.8, 51.2, 49.4, 47.7, 47.4, 47.2, 47.1, 46.9,44.4, 28.7, 28.6, 25.0; IR (neat): ν_(max)(cm⁻¹)=2965 (w), 1643 (s),1520 (w), 1449 (s), 1418 (s), 1358 (m), 1123 (m), 758 (m), 739 (s); HRMS(ESI+) calcd for C₃₄H₃₉N₃O₄ ([M+H]⁺) 554.3019. found 554.3019.

Example 19

Compound 10:

General procedure 2 was followed using31R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), benzoic acid (111 mg, 0.91 mmol) and (R)-(+)-methylbenzylisocyanide (119 mg, 123 μl, 0.91 mmol) giving 10 as a white solid, yield73%.

[α]_(D) ²⁰=−24.0° (c=0.25, MeCN). ¹H NMR (500.2 MHz, CDCl₃): δ 7.45-7.19(m, 11H), 6.24 dd, J=5.7, 2.9 Hz, 1H), 5.93 dd, J=5.7, 2.9 Hz, 1H),5.11-5.03 (m, 1H), 4.59 d, J=1.8 Hz, 1H), 3.53-3.49 (m, 1H), 3.40-3.35(m, 1H), 3.02-2.97 (m, 2H), 2.88-2.81 (m, 1H), 2.77-2.75 (m, 1H),1.48-1.39 (m, 2H), 1.45 (d, J=7.0 Hz, 2H); ¹³C NMR (125.8 MHz, CDCl₃): δ169.8, 169.8, 144.0, 136.4, 134.8, 134.3, 130.0, 128.5, 128.4, 126.9,126.4, 125.7, 62.0, 51.8, 51.5, 49.0, 47.0, 46.4, 45.5, 44.4, 22.7; IR(neat): ν_(max) (cm⁻¹)=3302 (w), 3239 (w), 3059 (w), 2665 (w), 2929 (w),1664 (s), 1559 (s), 1558 (s), 1427 (s), 1248 (m), 1020 (m), 698 (s), 667(m); HRMS (ESI+) calcd for C₂₅H₂₆N₂O₂ ([M+H]⁺) 387.2073. found 387.2067.

Example 20

Compound 11:

General procedure 2 was followed using31R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), benzoic acid (111 mg, 0.91 mmol) and (S)-(−)-methylbenzylisocyanide (119 mg, 123 μl, 0.91 mmol) giving 11 as a white solid, yield70%.

[α]_(D) ²⁰=−78.6° (c=0.28, MeCN). ¹H NMR (400.1 MHz, CDCl₃): δ 7.43-7.16(m, 11H), 6.24-6.19 (m, 1H), 5.97-5.90 (m, 1H), 5.10-5.01 (m, 1H), 4.52(bs, 1H), 3.61-3.56 (m, 1H), 3.47-3.44 (m, 1H), 3.09-3.06 (m, 1H), 2.99(bs, 1H), 2.93-2.87 (m, 1H), 2.80 (bs, 1H), 1.50-1.39 (m, 2H), 1.43 (d,J=6.8 Hz, 3H); ¹³C NMR (125.8 MHz, CDCl₃) 170.1, 169.9, 143.3, 136.5,134.8, 134.4, 130.1, 128.7, 128.5, 127.2, 126.5, 126.1, 62.4, 52.1,51.6, 49.1, 47.0, 46.5, 45.6, 44.9, 22.4; IR (neat): ν_(max)(cm⁻¹)=3281(m), 3281 (m), 2955 (m), 1638 (s), 1528 (s), 1397 (s), 1343 (m), 1227(m), 1117 (m), 700 (s); HRMS (ESI+) calcd for C₂₅H₂₆N₂O₂ ([M+H]⁺)387.2073. found 387.2067.

Example 21

Compound 12:

General procedure 2 was followed using1R,2S,6R,7S)-4-methyl-4-azatricyclo[5.2.1.0^(2,6)]dec-8-ene (6, 93 mg,0.70 mmol), Fmoc-L-Pro-OH (307 mg, 0.91 mmol) and t-butyl isocyanide (76mg, 103 μl, 0.91 mmol). The crude product was purified by columnchromatography (SiO₂, EtOAc (1): cyclohexane (2)). Simultaneous Fmocdeprotection and saponification according to literature procedure⁴followed by addition of 1.1 eq. TFA and purification using reversedphase chromatography (C₁₈, H₂O (1): EtOH (1)) gave 12 as a colorlesssolid, in 62% yield over two steps.

[α]_(D) ²⁰=−6.8° (c=0.30, MeCN). ¹H NMR (500.2 MHz, DMSO): δ 12.43 (bs,1H), 9.68-9.44 (m, 1H), 8.54 (bs, 1H), 8.19-8.14 (m, 1H), 6.29-6.25 (m,1H), 6.13 (dd, J=5.7, 2.9 Hz, 1H), 3.95 (bs, 1H), 3.66-3.59 (m, 1H),3.37-3.18 (m, 5H), 2.96 (bs, 2H), 2.79-2.73 (m, 1H), 2.50-2.38 (m, 4H),1.97-1.85 (m, 2H), 1.69-1.57 (m, 2H), 1.46-1.35 (m, 2H); ¹³C NMR (125.8MHz, CDCl₃) δ 172.7, 171.2, 165.8, 158.1, 157.9, 135.6, 134.8, 117.9,115.5, 62.9, 58.1, 50.9, 49.6, 49.0, 46.5, 46.4, 45.8, 44.1, 34.6, 33.8,27.9, 23.6; IR (neat): ν_(max) (cm⁻¹)=2949 (w), 1640 (s), 1175 (s) 1130(s), 833 (m), 719 (m); HRMS (ESI+) calcd for C₂₀H₂₆F₃N₃O₃ ([M+H]⁺)347.1845. found 348.1929.

Example 22 (S)-Methyl 2-cyclohexyl-2-(pyrazine-2-carboxamido)acetate (9)

Pyrazinecarboxylic acid (2.72 g, 21.9 mmol) was added to a solution ofL-cyclohexylglycine methyl ester (4.13 g, 19.9 mmol) in CH₂Cl₂ (100 ml)at room temperature under N₂, forming a white suspension. Triethylamine(6.33 ml, 4.62 g, 45.8 mmol) was added, followed bybenzotriazol-1-yloxy-tris-(dimethylamino)-phosphoniumhexafluorophosphate (BOP; 9.69 g, 21.9 mmol), which turned the reactionmixture from purple to an orange solution. After two days of stirring atroom temperature the reaction mixture was washed two times with 50 mlsaturated Na₂CO₃, followed by the washing of the aqueous layers withCH₂Cl₂ (2×50 ml). The organic layers were collected and dried withMgSO₄, followed by concentration in vacuo. Purification by silica gelflash chromatography (c-Hex:EtOAc=2:1 with 0.5% triethylamine) afforded9 (5.28 g, 19.03 mmol, 96%) as a yellow oil that solidified uponstanding to give a white solid.

[α]_(D) ²⁰=+42.5 (c=1.13, CHCl₃); ¹H NMR (250.13 MHz, CDCl₃) δ=9.39 (d,J=1.25 Hz, 1H), 8.76 (d, J=2.5 Hz, 1H), 8.57 (t, J=1.5 Hz, 1H), 8.25 (d,J=8.8 Hz, 1H), 4.74 (dd, J=5.5, 9.3 Hz, 1H), 3.78 (s, 3H), 1.96 (m, 1H),1.77 (m, 5H), 1.24 (m, 5H); ¹³C NMR (62.90 MHz, CDCl₃): δ=172.0 (C),162.8 (C), 147.4 (CH), 144.5 (CH), 144.1 (C), 142.7 (CH), 57.0 (CH),52.3 (CH₃), 41.2 (CH), 29.7 (CH₂), 28.4 (CH₂), 26.0 (CH₂); IR (neat):ν_(max) (cm⁻¹)=3374 (m), 2920 (s), 2845 (w), 1740 (s), 1665 (s); HRMS(ESI, 4500 V): m/z calcd. for C₁₄H₁₉N₃O₃Na⁺ ([M+Na]⁺) 300.1319. found300.1319.

Example 23

(S)-2-cyclohexyl-2-(pyrazine-2-carboxamido)acetic acid (10)

A solution of 1 M NaOH (12 ml, 12 mmol) was added to a solution of 9(2.77 g, 10 mmol) in THF (25 ml) at 0° C. MeOH was added to the formedsuspension, to give a clear, colorless solution. The reaction mixturewas stirred overnight at room temperature, followed by concentration invacuo. The pH of the aqueous layer was set on 3.5 with a 1 M KHSO₄solution and was extracted with EtOAc (2×25 ml). The mixture was driedwith Na₂SO₄, filtered, and concentrated in vacuo, to give 10 (2.49 g,9.45 mmol, 95%) as a white solid.

[α]_(D) ²⁰=+50.9 (c=1.06, CHCl₃); ¹H NMR (250.13 MHz, CDCl₃): δ=9.38 (d,J=1.5 Hz, 1H), 8.78 (d, J=2.5 Hz, 1H), 8.58 (dd, J=1.5, 2.5 Hz, 1H),8.27 (d, J=9.0, 1H), 4.77 (dd, J=4.3, 5.0 Hz, 1H), 2.00 (m, 1H), 1.76(m, 5H), 1.37 (m, 5H); ¹³C NMR (62.90 MHz, CDCl₃): δ=175.7 (C), 163.0(C), 147.2 (CH), 144.3 (CH), 144.2 (C), 142.0 (CH), 56.9 (CH), 40.9(CH), 29.7 (CH₂), 28.1 (CH₂), 25.9 (CH₂); IR (neat): ν_(max) (cm⁻¹)=3383(m), 2928 (s), 2852 (w), 1713 (m), 1676 (s), 1518 (s); HRMS (ESI, 4500V): m/z calcd. For C₁₃H₁₇N₃O₃Na⁺ ([M+Na]⁺) 286.1162. found 286.1158.

Example 23

(S)-methyl2-((S)-2-cyclohexyl-2-(pyrazine-2-carboxamido)-acetamido)-3,3-dimethylbutanoate(11)

10 (0.653 g, 4.5 mmol) was added to a solution of H-Tle-OMe (0.653 g,4.5 mmol) in DMF (40 ml).1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide-HCl (EDC-HCl; 0.919 g,6.75 mmol) was added to this colorless solution followed by1-hydroxy-7-azabenzotriazole (HOAt; 1.035 g, 5.4 mmol) giving a brightyellow solution. The reaction mixture was stirred for 3 days andafterwards concentrated in vacuo. The formed yellow solid was dissolvedin EtOAc, washed with 40 ml saturated aqueous ammonium chloride solutionand 40 ml of saturated aqueous NaHCO₃ solution. The organic layers werecollected, dried with MgSO₄ and concentrated in vacuo to give 11 (1.48g, 3.78 mmol, 84%) as a white solid.

[α]_(D) ²⁰=−2.0 (c=1.0, CHCl₃); ¹H NMR (250.13 MHz, CDCl₃): δ=9.39 (d,J=1.5 Hz, 1H), 8.76 (d, J=2.3 Hz, 1H), 8.55 (dd, J=2.4, 1.8 Hz, 1H),8.29 (d, J=8.1, 1H), 6.40 (d, J=9.3 Hz, 1H), 4.46 (m, 2H), 3.74 (s, 3H),1.81 (m, 1H), 1.76 (m, 4H), 1.24 (m, 6H), 0.96 (s, 12H); ¹³C NMR (62.90MHz, CDCl₃): δ=171.7 (C), 170.4 (C), 163.0 (C), 147.5 (CH), 144.5 (CH),144.2 (C), 142.7 (CH), 60.2 (CH₃), 58.4 (CH), 51.9 (CH), 40.5 (CH), 31.7(C), 29.7 (CH₂), 28.7 (CH₂), 26.6 (CH₃), 25.9 (CH₂); IR (neat): ν_(max)(cm⁻¹)=3350 (m), 2928 (m), 2853 (w), 1738 (s), 1686 (s), 1640 (s), 1520(s); HRMS (ESI, 4500 V): m/z calcd. for C₂₀H₃₀N₄O₄Na⁺ ([M+Na]⁺)413.2159. found 413.2169.

Example 24(S)-2-((S)-2-cyclohexyl-2-(pyrazine-2-carboxamido)acetamido)-3,3-dimethylbutanoicacid (2)

A solution of 1 M NaOH (0.94 ml, 0.94 mmol) was added to a solution of11 (0.31 g, 0.78 mmol) in THF (3 ml) at 0° C. MeOH was added to theformed suspension, to give a clear and colourless solution. The reactionmixture was stirred overnight at room temperature, followed byconcentration in vacuo. The pH of this aqueous layer was set to 3.5 with1 M KHSO₄ and subsequently extracted with EtOAc (2×10 ml). The mixturewas dried with Na₂SO₄, filtered, and concentrated in vacuo, to give 2(0.28 g, 0.75 mmol, 95%) as a white solid.

[α]_(D) ²⁰=+21.7 (c=1.015, CHCl₃); ¹H NMR (250.13 MHz, CDCl₃): δ=9.39(d, J=1.3 Hz, 1H), 8.77 (d, J=2.5 Hz, 1H), 8.57 (dd, J=1.5, 2.5 Hz, 1H),8.35 (d, J=9 Hz, 1H), 6.70 (d, J=9.0 Hz, 1H), 4.45 (t, J=8.8 Hz, 1H),4.42 (d, J=9.2 Hz, 1H), 1.94 (m, 1H), 1.71 (m, 5H), 1.20 (m, 5H), 1.01(s, 9H); ¹³C NMR (62.90 MHz, CDCl₃): δ=173.4 (C), 170.5 (C), 163.3 (C),147.4 (CH), 144.4 (CH), 144.2 (C), 142.8 (CH), 58.4 (CH), 51.9 (CH),40.4 (CH), 34.7 (C), 29.8 (CH₂), 28.6 (CH₂), 26.6 (CH₃), 25.8 (CH₂); IR(neat): ν_(max) (cm⁻¹)=3335 (w), 2930 (m), 1726 (m), 1663 (s), 1514 (s);HRMS (ESI, 4500 V): m/z calc. for C₁₉H₂₉N₄O₄Na⁺ ([M+Na]⁺) 399.2003.found 399.2013.

Example 25

(S)-2-formamido-1-pentanol (12)

(S)-2-amino-1-pentanol (1.00 g, 9.7 mmol) was dissolved in ethylformate(7.84 ml, 7.19 g, 97 mmol). This reaction mixture was refluxed at 80° C.for 4 hours, followed by stirring overnight at room temperature. Thecolourless solution was concentrated in vacuo and stirred for 1 hour ina 10 mol % K₂CO₃ in MeOH (25 ml). Afterwards, the pH was set to 7 withDOWEX 50wx8, followed by filtration and concentration in vacuo to give12 (1.26 g, 9.61 mmol, 99%).

[α]_(D) ²⁰=−29.6 (c=1.15, CHCl₃); ¹H NMR (250.13 MHz, CDCl₃): δ=8.20 (s,1H), 5.81 (bs, 1H), 4.04 (m, 1H), 2.11 (b, 1H), 1.47 (m, 4H), 0.94 (t,J=7.0 Hz, 3H); ¹³C NMR (62.90 MHz, CDCl₃): 161.8 (C), 65.1 (CH₂), 50.6(CH), 33.2 (CH₂), 19.2 (CH₂), 13.9 (CH₃); IR (neat): ν_(max) (cm⁻¹)=3248(s), 2957 (m), 1651 (s), 1528 (m), 1381 (m); HRMS (ESI, 4500 V): m/zcalcd. for C₆H₁₃NO₂Na⁺ ([M+Na]⁺) 154.0838. found 154.0835.

Example 26

(S)-2-formamidopentanal

(7). Dess-Martin periodinane (5.514 g, 13 mmol) was added to a solutionof (S)-2-formamido-1-pentanol (12, 1.31 g, 10 mmol) in CH₂Cl₂ (100 ml)at room temperature. The white suspension was stirred for 2 days andsubsequently 35 ml MeOH was added and stirred for 30 minutes. Theresulting suspension was filtrated and the filtrate was concentrated invacuo. The crude product was purified by silica gel flash chromatography(cHex:EtOAc=1:4) to give 7 (1.08 g, 8.29 mmol, 83%) as a white solid.NMR analysis indicates that 7 is in equilibrium with its cyclic dimer.

[α]_(D) ²⁰=+37.6 (c=0.745, CHCl₃); ¹H NMR assigned to the monomer(250.13 MHz, CDCl₃): δ=8.22 (s, 1H), 7.84 (s, 1H), 7.10 (m, 1H), 5.31(m, 1H), 1.52 (m, 4H), 0.95 (m, 3H); ¹³C NMR assigned to the monomer(100.61 MHz, CDCl₃): 198.8 (CH), 161.7 (CH), 57.4 (CH), 30.8 (CH₂), 18.4(CH₂), 13.7 (CH₃); ¹H NMR assigned to the dimer (400.13 MHz, CDCl₃) 8.22(s, 2H), 5.26 (m, 2H), 3.72 (m, 2H) 1.52 (m, 8H), 0.95 (m, 6H;) ¹³C NMR(100.61 MHz, CDCl₃) assigned to the dimer: 161.7 (CH), 89.8 (CH), 63.1(CH), 30.8 (CH2), 18.4 (CH2), 13.7 (CH3); IR (neat): ν_(max) (cm⁻¹):3325 (s), 2959 (s), 1649 (s), 1530 (s), 1381 (m), 1123 (w); HRMS (ESI,4500 V): m/z calc. for C₆H₁₂NO₂ ⁺ ([M+H]⁺) 130.0863. found 130.0858.

It was noted that the dimer exists as a mixture of diastereomers.

Example 27

(3S)-2-acetoxy-N-cyclopropyl-3-formamidohexanoyl amide (13) From 7:

Aldehyde 7 (0.892 g, 6.91 mmol) was added to a solution of cyclopropylisocyanide (0.410 g, 6.12 mmol) in CH₂Cl₂ (110 ml) and stirred for 5minutes at room temperature. Acetic acid (0.711 ml, 0.747 g, 12.44 mmol)was added and the yellow reaction mixture was stirred for 3 days at roomtemperature. The reaction mixture was washed twice with 100 ml saturatedNa₂CO₃, followed by drying with Na₂SO₄ and concentration in vacuo. Thecrude was purified by silica gel flash chromatography (5% MeOH inCH₂Cl₂, 1% triethylamine).(3S)-2-acetoxy-N-cyclopropyl-3-formamidohexanoyl amide (0.99 g, 3.87mmol, 56%) was obtained as a white solid as a 78:22 mixture ofdiastereomers.

From 12:

Dess Martin periodinane (5.66 g, 12.3 mmol) was added to a solution of(S)—N-(1 hydroxypentan-2-yl)formamide (1.15 g, 8.8 mmol) in CH₂Cl₂ (12ml) at room temperature. The white suspension was stirred for 60 minutesand subsequently cyclopropyl isocyanide (0.74 g, 10.0 mmol) was addedand stirred for 48 hours. The resulting suspension was filtrated andwashed twice with 10 ml saturated Na₂CO₃, followed by drying with Na₂SO₄and concentration in vacuo. The crude product was purified by silica gelflash chromatography (5% MeOH in CH₂Cl₂, 1% triethylamine) to give 13(1.34 g, 5.22 mmol, 60%) as a pale yellow solid as a 78:22 mixture ofdiastereomers.

¹H NMR (130° C., 400.13 MHz, DMSO-d₆): δ=8.03 (s, 1H), 7.52 (m, 1H),7.30 (m, 1H), 4.89 (d, J=4.4, 1H), 4.28 (m, 1H), 2.65 (m, 1H), 2.17 (s,3H), 1.27-1.47 (m, 4H), 0.89 (t, J=7.2, 3H), 0.63 (m, 2H), 0.48 (m, 2H);¹³C NMR (125.78 MHz, DMSO-d₆): δ=169.8 (C), 168.5 (C), 160.6 (CH), 74.4(CH), 47.5 (CH), 22.2 (CH), 18.4 (CH₃), 13.6 (CH₃), 5.7 (CH₂); IR(neat): ν_(max) (cm⁻¹) 3283 (s), 2961 (w), 1744 (m), 1661 (s), 1530 (s),1238 (s); HRMS (ESI, 4500 V): m/z calcd. for C₁₂H₂₀N₂O₄Na⁺ ([M+Na]⁺)279.1315. found 279.1325.

Example 28

(3S)-2-acetoxy-N-cyclopropyl-3-isocyano-hexanoyl amide (4)

N-methylmorpholine (0.57 ml, 0.562 g, 5.56 mmol) was added to a solutionof (S)-1-(cyclopropylamino)-3-formamido-1-oxohexan-2-yl acetate (0.713g, 2.78 mmol) in CH₂Cl₂ (40 ml) at room temperature. The reactionmixture was cooled to −78° C. and triphosgene (0.289 g, 0.97 mmol) wasquickly added and stirred for 5 minutes at this temperature. Theresulting yellow solution was warmed up to −30° C. and was stirred foranother 3 h. Subsequently, the reaction was quenched with water andextracted twice with CH₂Cl₂ (40 ml). The organic layers were collected,dried with Na₂SO₄ and concentrated in vacuo. The crude product waspurified by silica gel flash chromatography (2% MeOH in CH₂Cl₂) to give4 (0.578 g, 2.42 mmol, 87%) as a white solid.

¹H NMR (250.13 MHz, CDCl₃): δ=6.28 (s, 1H), 5.25 (d, J=2.5 Hz, 1H), 4.2(m, 1H), 2.74 (m, 1H), 2.24 (s, 3H), 1.55 (m, 4H), 0.96 (m, 3H), 0.84(m, 2H), 0.60 (m, 2H); ¹³C NMR (62.90 MHz, CDCl₃): δ=169.7 (C), 168.3(C), 74.4 (CH), 47.5 (CH), 22.0 (CH), 20.6 (CH₃), 18.5 (CH₂), 13.5(CH₃), 5.5 (CH₂); IR (neat): ν_(max) (cm⁻¹): 3267 (s), 2959 (m), 1745(m), 1643 (s), 1512 (m), 1221 (s); HRMS (ESI, 4500 V): m/z calcd. forC₁₂H₁₈N₂O₃Na⁺ ([M+Na]⁺) 261.1210. found 261.1214.

Example 29

Compound 14.

Isocyanide 4 (0.549 g, 2.3 mmol) was dropwise added to a solution ofimine 3 (0.252 g, 2.3 mmol) and carboxylic acid 2 (0.602 g, 1.60 mmol)in CH₂Cl₂ (5 ml) at room temperature. This yellow solution was stirredfor 72 hours and afterwards diluted with 5 ml CH₂Cl₂. The reactionmixture was washed twice with saturated Na₂CO₃ solution (10 ml) andtwice with saturated NH₄Cl. The organic layers were collected, driedwith MgSO₄ and concentrated in vacuo. The crude product was purified bysilica gel flash chromatography (5% MeOH in CH₂Cl₂) to give 14 (0.876 g,1.21 mmol, 76%) as a mixture of diastereomers.

¹H NMR (500.23 MHz, CDCl₃): δ=9.50 (s, 1H), 8.75 (d, J=2.5, 1H), 8.59(s, 1H), 8.35 (d, J=9.0, 1H), 6.84 (d, J=9.0, 1H), 6.44 (s, 1H), 5.20(d, J=3.0, 1H), 4.74 (d, J=9.5, 1H), 4.58 (t, J=7.5, 1H), 4.38 (m, 1H),3.37 (d, J=6.0, 1H), 2.82 (m, 1H), 2.69 (m, 1H), 2.11 (s, 3H), 1.26 (s,2H), 0.97 (s, 9H), 0.86 (m, 3H), 0.84-2.00 (m, 21H), 0.76 (m, 2H), 0.51(m, 2H); ¹³C NMR (125.78 MHz, CDCl₃): δ=170.5 (C), 169.3 (C), 162.9 (C),147.4 (CH), 144.6 (CH), 144.2 (C), 142.8 (CH), 74.4 (CH), 66.6 (CH),58.3 (CH), 56.6 (CH), 54.5 (CH₂), 44.9 (CH), 43.0 (CH), 41.3 (CH), 35.5(C), 26.4 (CH₃), 20.8 (CH₃), 19.1 (CH₂), 13.8 (CH₃), 6.6 (CH₂); ν_(max)(cm⁻¹): 3306 (m), 2928 (m), 2931 (m), 1743 (w), 1655 (s), 1520 (m), 1219(m); HRMS (ESI, 4500 V): m/z calcd. for C₃₈H₅₇N₇O₇Na⁺ ([M+Na]⁺)746.4212. found 746.4107.

Example 30

Telaprevir (1).

250 μl of saturated K₂CO₃ was added to a solution of 14 (0.514 g, 0.75mmol) in MeOH (20 ml) at room temperature. The reaction mixture wasstirred for 30 minutes at room temperature resulting in a pale yellowsuspension. After full conversion (as judged by TLC analysis), thereaction mixture was washed with 20 ml brine, the aqueous layer waswashed again with 10 ml CH₂Cl₂ (2×). The organic layers were collected,dried with MgSO₄ and concentrated in vacuo, to yield a pale yellowsolid. The yellow solid was dissolved in CH₂Cl₂ (10 ml) and Dess-Martinperiodinane (0.650 g, 1.532 mmol) was added at room temperature. Thereaction mixture was stirred overnight before adding saturated NaHCO₃solution (10 ml) and saturated Na₂S₂O₃ solution (10 ml). This mixturewas stirred for 10 minutes, separated and the aqueous layers were washedwith EtOAc (2×10 ml). The organic layers were collected, dried withMgSO₄ and concentrated in vacuo to give the crude product as an 83:13:4mixture of diastereomers. After silica gel flash chromatography (1% MeOHin CH₂Cl₂), 1 (0.412 mg, 0.61 mmol, 80%) was obtained as a white solid.

¹H NMR (500.23 MHz, DMSO-d₆): δ=9.19 (d, J=1.4 Hz, 1H), 8.91 (d, J=24.5Hz, 1H), 8.76 (dd, J=1.5, 2.5 Hz, 1H), 8.71 (d, J=5.3 Hz, 1H), 8.49 (d,J=9.2 Hz, 1H), 8.25 (d, J=6.8 Hz, 1H), 8.21 (d, J=8.9 Hz, 1H), 4.94 (m,1H), 4.68 (dd, J=6.5, 9.0 Hz, 1H), 4.53 (d, J=9.0 Hz, 1H), 4.27 (d,J=3.5 Hz, 1H), 3.74 (dd, J=8.0, 10 Hz, 1H), 2.74 (m, 1H), 3.64 (d, J=3.5Hz, 1H), 0.92 (s, 9H), 0.87 (t, 3H), 0.84-1.40 (m, 23H), 0.65 (m, 2H),0.56 (m, 2H); ¹³C NMR (125.78 MHz, CDCl₃): δ=197.0 (C), 171.8 (C), 170.4(C), 169.0 (C), 162.1 (C), 161.9 (C), 147.9 (CH), 144.0 (C), 143.4 (CH),56.4 (CH), 56.3 (CH), 54.2 (CH), 53.4 (CH), 42.3 (CH), 41.3 (CH), 32.1(CH), 31.8 (CH), 31.6 (CH), 29.1 (CH), 28.0 (CH), 26.4 (CH₃); ν_(max)(cm⁻¹): 3302 (m), 2928 (m), 2858 (w), 1658 (s), 1620 (s), 1561 (s), 1442(m); HRMS (ESI, 4500 V): m/z calcd. for C₃₆H₅₃N₇O₆Na⁺ ([M+Na]⁺)702.3950. found 702.3941.

REFERENCES

-   1. S. Michaelis, S. Blechert, Chem. Eur. J. 2007, 13, 2358-2368-   2. V. Köhler, K. R. Bailey, A. Znabet, J. Raftery, M.    Helliwell, N. J. Turner, Angew. Chem. Int. Ed. 2010, 49, 2182-2184.-   3. N. Elders, E. Ruijter, F. J. J. de Kanter, E. Janssen, M.    Lutz, A. L. Spek, R. V. A. Orru Chem. Eur. J. 2009, 6096-6099.-   4. V. Theodorou, K. Skobridis, A. G. Tzakos, V. Ragoussis    Tetrahedron Lett. 2007, 48, 8230-8233.

While the present invention has been described with reference tospecific preferred embodiments, it should be appreciated that variationsare possible without departing from the scope of the invention.Therefore, the invention is not intended to be limited by thedescription in the specification but only by the language of the claimsand equivalents thereof.

1. A process for stereo-selectively preparing a compound of formula I ordiastereomer thereof:

comprising reacting a compound of formula II or a diastereomer thereof:

with a compound of formula III:R³—COOH  (III) and a compound of formula IV:R⁴—NC  (IV) wherein R¹ represents each independently, or jointly asubstituted or unsubstituted alkyl, alkenyl, alkynyl, aromatic ornon-aromatic, mono-, di- or tricyclic, or heterocyclic group, R²represents a hydrogen atom, a substituted or unsubstituted alkyl,alkenyl, alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic, orheterocyclic group, and R³ represents a substituted or unsubstitutedalkyl, alkenyl, or alkynyl, or an aromatic or non-aromatic aromatic ornon-aromatic, mono-, di- or tricyclic, or heterocyclic group.
 2. Theprocess according to claim 1, wherein both substituents R¹ jointly forma substituted or unsubstituted 3-, 4-, 5-, 6-, 7- or 8-membered ringstructure.
 3. The process according to claim 2, wherein R¹ is chosensuch that the compound of formula I has a structure of formula V:


4. The process according to claim 2, wherein R¹ is chosen such that thecompound of formula I has a structure of formula VI:


5. The process according to claim 2, wherein R¹ is chosen such that thecompound of formula I has a structure of formula VII:


6. The process according to claim 1, wherein R² represents a dipeptideof formula VIII:

wherein R^(a) and R^(b) each independently represents a hydrogen atom, ahalogen atom, C₁₋₁₄ alkyl optionally substituted by halogen, acycloalkyl group, an aryl group, a lower alkoxy group, a lower thioalkylgroup, a cycloalkyloxy group, an aralkyloxy group or an alkanoyl group;a hydroxyl group, a nitro group, a formyl group, an amino group whichmay be protected or substituted, a cycloalkyloxy, aralkyloxy, alkanoyl,ureido or mono-, di- or tricyclic heterocyclic group, all of whichgroups may optionally be substituted.
 7. The process according to claim1, wherein the compound of formula IV has a structure of formula IX:

wherein R^(d), R^(e) and R^(f) each independently represents a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl, alkenyl,alkynyl, aromatic or non-aromatic, mono-, di- or tricyclic and/or aheterocyclic group.
 8. The process according to claim 1, furthercomprising: preparing the compound of formula IIa or IIb bydesymmetrization of 3,4-substituted meso-pyrrolidine.
 9. The processaccording to claim 8, wherein the desymmetrization comprises treatingthe meso-pyrrolidine with an enzyme capable of catalysing oxidation ofan amine in an enantio selective manner.
 10. The method according toclaim 9, wherein the enzyme is a monoamine oxidase N derived fromAspergillus niger.
 11. The process according to claim 1, wherein R² ischosen such that the compound of formula III has a structure of formulaXV:


12. The process according to claim 1, wherein R³ is chosen such that thecompound of formula IV has a structure of formula XVI:


13. The process according to claim 12, further comprising: isolatingfrom a reaction product a compound of formula XVII:


14. The process according to claim 13, further comprising: subjectingthe compound of formula XVII to a saponification, followed by aselective oxidation to form a compound of formula XVIII:


15. The process according to claim 14, wherein the saponification iscarried out by contacting the compound of formula XVII with an alkalinemetal carbonate in a suitable solvent, to obtain a saponified alcoholproduct.
 16. The process according to claim 15, wherein the selectiveoxidation is carried out by contacting the saponified alcohol productwith a suitable oxidant in a suitable solvent.
 17. A compound obtainedby the process according to claim 1, or an enantiomer, stereoisomer,rotamer, tautomer, racemate, pharmaceutically acceptable salt or solvatethereof. 18-24. (canceled)
 25. A method for catalyzing an organochemicalreaction, comprising adding a compound obtained from the process ofclaim 1 to the organochemical reaction.
 26. (canceled)
 27. A compositioncomprising a compound of formula I obtained from the process of claim 1and a pharmaceutically acceptable carrier, diluent or excipient.
 28. Theprocess according to claim 1, further comprising: formulating a compoundof formula (I) and optionally a utilizable carrier to a pharmaceuticalcomposition.
 29. A method for treating a condition associated with viralinfections in a subject, comprising: administering to a subject in needthereof at least one compound of formula (I) obtained from the processof claim 1 or a pharmaceutically acceptable salt or N-oxide thereof.30-31. (canceled)